update button margin on appearance page

* more safely delete the roblox instance

* assertreadonly the whole directory

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -45,6 +45,16 @@ body:
       description: Provide a comprehensive description of the problem you're facing. Don't forget to attach any additional resources you may have, such as log files and screenshots.
     validations:
       required: true
+  - type: textarea
+    id: repro-steps
+    attributes:
+      label: How do you reproduce the problem?
+      description: Include the steps to reproduce the problem from start to finish. Include details such as FastFlags you added and settings you changed.
+      placeholder: |
+        1. Go to '...'
+        2. Click on '...'
+        3. Scroll down to '...'
+        4. See error
   - type: textarea
     id: log
     attributes:

Bloxstrap/App.xaml.cs

@@ -181,6 +181,22 @@ namespace Bloxstrap
             }
         }
 
+        public static void AssertWindowsOSVersion()
+        {
+            const string LOG_IDENT = "App::AssertWindowsOSVersion";
+
+            int major = Environment.OSVersion.Version.Major;
+            if (major < 10) // Windows 10 and newer only
+            {
+                Logger.WriteLine(LOG_IDENT, $"Detected unsupported Windows version ({Environment.OSVersion.Version}).");
+
+                if (!LaunchSettings.QuietFlag.Active)
+                    Frontend.ShowMessageBox(Strings.App_OSDeprecation_Win7_81, MessageBoxImage.Error);
+
+                Terminate(ErrorCode.ERROR_INVALID_FUNCTION);
+            }
+        }
+
         protected override void OnStartup(StartupEventArgs e)
         {
             const string LOG_IDENT = "App::OnStartup";
@@ -213,6 +229,8 @@ namespace Bloxstrap
 #endif
             }
 
+            Logger.WriteLine(LOG_IDENT, $"OSVersion: {Environment.OSVersion}");
+
             Logger.WriteLine(LOG_IDENT, $"Loaded from {Paths.Process}");
             Logger.WriteLine(LOG_IDENT, $"Temp path is {Paths.Temp}");
             Logger.WriteLine(LOG_IDENT, $"WindowsStartMenu path is {Paths.WindowsStartMenu}");
@@ -292,6 +310,7 @@ namespace Bloxstrap
             {
                 Logger.Initialize(true);
                 Logger.WriteLine(LOG_IDENT, "Not installed, launching the installer");
+                AssertWindowsOSVersion(); // prevent new installs from unsupported operating systems
                 LaunchHandler.LaunchInstaller();
             }
             else

Bloxstrap/Bloxstrap.csproj

@@ -7,8 +7,8 @@
     <UseWPF>true</UseWPF>
     <UseWindowsForms>True</UseWindowsForms>
     <ApplicationIcon>Bloxstrap.ico</ApplicationIcon>
-    <Version>2.8.6</Version>
+    <Version>2.9.0</Version>
-    <FileVersion>2.8.6</FileVersion>
+    <FileVersion>2.9.0</FileVersion>
     <ApplicationManifest>app.manifest</ApplicationManifest>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludeSourceRevisionInInformationalVersion>false</IncludeSourceRevisionInInformationalVersion>
@@ -31,7 +31,8 @@
 
   <ItemGroup>
     <EmbeddedResource Include="Resources\CustomBootstrapperSchema.json" />
-    <EmbeddedResource Include="Resources\CustomBootstrapperTemplate.xml" />
+    <EmbeddedResource Include="Resources\CustomBootstrapperTemplate_Blank.xml" />
+    <EmbeddedResource Include="Resources\CustomBootstrapperTemplate_Simple.xml" />
     <EmbeddedResource Include="Resources\Icon2008.ico" />
     <EmbeddedResource Include="Resources\Icon2011.ico" />
     <EmbeddedResource Include="Resources\Icon2017.ico" />
@@ -54,10 +55,10 @@
 
   <ItemGroup>
     <PackageReference Include="AvalonEdit" Version="6.3.0.90" />
-    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.2" />
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.0" />
     <PackageReference Include="DiscordRichPresence" Version="1.2.1.24" />
-    <PackageReference Include="Markdig" Version="0.37.0" />
+    <PackageReference Include="Markdig" Version="0.40.0" />
-    <PackageReference Include="Microsoft.Windows.CsWin32" Version="0.3.106">
+    <PackageReference Include="Microsoft.Windows.CsWin32" Version="0.3.183">
       <!--<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>-->
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>

Bloxstrap/Bootstrapper.cs

@@ -58,6 +58,7 @@ namespace Bloxstrap
         private double _taskbarProgressIncrement;
         private double _taskbarProgressMaximum;
         private long _totalDownloadedBytes = 0;
+        private bool _packageExtractionSuccess = true;
 
         private bool _mustUpgrade => String.IsNullOrEmpty(AppData.State.VersionGuid) || !File.Exists(AppData.ExecutablePath);
         private bool _noConnection = false;
@@ -78,7 +79,15 @@ namespace Bloxstrap
 
             // https://github.com/icsharpcode/SharpZipLib/blob/master/src/ICSharpCode.SharpZipLib/Zip/FastZip.cs/#L669-L680
             // exceptions don't get thrown if we define events without actually binding to the failure events. probably a bug. ¯\_(ツ)_/¯
-            _fastZipEvents.FileFailure += (_, e) => throw e.Exception;
+            _fastZipEvents.FileFailure += (_, e) =>
+            {
+                // only give a pass to font files (no idea whats wrong with them)
+                if (!e.Name.EndsWith(".ttf"))
+                    throw e.Exception;
+
+                App.Logger.WriteLine("FastZipEvents::OnFileFailure", $"Failed to extract {e.Name}");
+                _packageExtractionSuccess = false;
+            };
             _fastZipEvents.DirectoryFailure += (_, e) => throw e.Exception;
             _fastZipEvents.ProcessFile += (_, e) => e.ContinueRunning = !_cancelTokenSource.IsCancellationRequested;
 
@@ -179,6 +188,8 @@ namespace Bloxstrap
             }
 #endif
 
+            App.AssertWindowsOSVersion();
+
             // ensure only one instance of the bootstrapper is running at the time
             // so that we don't have stuff like two updates happening simultaneously
 
@@ -221,6 +232,8 @@ namespace Bloxstrap
                 }
             }
 
+            bool allModificationsApplied = true;
+
             if (!_noConnection)
             {
                 if (AppData.State.VersionGuid != _latestVersionGuid || _mustUpgrade)
@@ -231,7 +244,7 @@ namespace Bloxstrap
 
                 // we require deployment details for applying modifications for a worst case scenario,
                 // where we'd need to restore files from a package that isn't present on disk and needs to be redownloaded
-                await ApplyModifications();
+                allModificationsApplied = await ApplyModifications();
             }
 
             // check registry entries for every launch, just in case the stock bootstrapper changes it back
@@ -245,7 +258,15 @@ namespace Bloxstrap
                 await mutex.ReleaseAsync();
 
             if (!App.LaunchSettings.NoLaunchFlag.Active && !_cancelTokenSource.IsCancellationRequested)
+            {
+                // show some balloon tips
+                if (!_packageExtractionSuccess)
+                    Frontend.ShowBalloonTip(Strings.Bootstrapper_ExtractionFailed_Title, Strings.Bootstrapper_ExtractionFailed_Message, ToolTipIcon.Warning);
+                else if (!allModificationsApplied)
+                    Frontend.ShowBalloonTip(Strings.Bootstrapper_ModificationsFailed_Title, Strings.Bootstrapper_ModificationsFailed_Message, ToolTipIcon.Warning);
+
                 StartRoblox();
+            }
 
             await mutex.ReleaseAsync();
 
@@ -303,14 +324,6 @@ namespace Bloxstrap
                 clientVersion = await Deployment.GetInfo();
             }
 
-            if (clientVersion.IsBehindDefaultChannel)
-            {
-                App.Logger.WriteLine(LOG_IDENT, $"Resetting channel from {Deployment.Channel} because it's behind production");
-
-                Deployment.Channel = Deployment.DefaultChannel;
-                clientVersion = await Deployment.GetInfo();
-            }
-
             key.SetValueSafe("www.roblox.com", Deployment.IsDefaultChannel ? "" : Deployment.Channel);
 
             _latestVersionGuid = clientVersion.VersionGuid;
@@ -649,7 +662,28 @@ namespace Bloxstrap
         #endregion
 
         #region Roblox Install
-        private void CleanupVersionsFolder()
+        private static bool TryDeleteRobloxInDirectory(string dir)
+        {
+            string clientPath = Path.Combine(dir, "RobloxPlayerBeta.exe");
+            if (!File.Exists(dir))
+            {
+                clientPath = Path.Combine(dir, "RobloxStudioBeta.exe");
+                if (!File.Exists(dir))
+                    return true; // ok???
+            }
+
+            try
+            {
+                File.Delete(clientPath);
+                return true;
+            }
+            catch (Exception)
+            {
+                return false;
+            }
+        }
+
+        public static void CleanupVersionsFolder()
         {
             const string LOG_IDENT = "Bootstrapper::CleanupVersionsFolder";
 
@@ -659,6 +693,13 @@ namespace Bloxstrap
 
                 if (dirName != App.State.Prop.Player.VersionGuid && dirName != App.State.Prop.Studio.VersionGuid)
                 {
+                    Filesystem.AssertReadOnlyDirectory(dir);
+
+                    // check if it's still being used first
+                    // we dont want to accidentally delete the files of a running roblox instance
+                    if (!TryDeleteRobloxInDirectory(dir))
+                        continue;
+
                     try
                     {
                         Directory.Delete(dir, true);
@@ -927,10 +968,12 @@ namespace Bloxstrap
             _isInstalling = false;
         }
 
-        private async Task ApplyModifications()
+        private async Task<bool> ApplyModifications()
         {
             const string LOG_IDENT = "Bootstrapper::ApplyModifications";
 
+            bool success = true;
+
             SetStatus(Strings.Bootstrapper_Status_ApplyingModifications);
 
             // handle file mods
@@ -1006,7 +1049,7 @@ namespace Bloxstrap
             foreach (string file in Directory.GetFiles(Paths.Modifications, "*.*", SearchOption.AllDirectories))
             {
                 if (_cancelTokenSource.IsCancellationRequested)
-                    return;
+                    return true;
 
                 // get relative directory path
                 string relativeFile = file.Substring(Paths.Modifications.Length + 1);
@@ -1038,10 +1081,18 @@ namespace Bloxstrap
                 Directory.CreateDirectory(Path.GetDirectoryName(fileVersionFolder)!);
 
                 Filesystem.AssertReadOnly(fileVersionFolder);
-                File.Copy(fileModFolder, fileVersionFolder, true);
+                try
-                Filesystem.AssertReadOnly(fileVersionFolder);
+                {
-
+                    File.Copy(fileModFolder, fileVersionFolder, true);
-                App.Logger.WriteLine(LOG_IDENT, $"{relativeFile} has been copied to the version folder");
+                    Filesystem.AssertReadOnly(fileVersionFolder);
+                    App.Logger.WriteLine(LOG_IDENT, $"{relativeFile} has been copied to the version folder");
+                }
+                catch (Exception ex)
+                {
+                    App.Logger.WriteLine(LOG_IDENT, $"Failed to apply modification ({relativeFile})");
+                    App.Logger.WriteException(LOG_IDENT, ex);
+                    success = false;
+                }
             }
 
             // the manifest is primarily here to keep track of what files have been
@@ -1088,7 +1139,7 @@ namespace Bloxstrap
                 if (package is not null)
                 {
                     if (_cancelTokenSource.IsCancellationRequested)
-                        return;
+                        return true;
 
                     await DownloadPackage(package);
                     ExtractPackage(package, entry.Value);
@@ -1099,6 +1150,11 @@ namespace Bloxstrap
             App.State.Save();
 
             App.Logger.WriteLine(LOG_IDENT, $"Finished checking file mods");
+
+            if (!success)
+                App.Logger.WriteLine(LOG_IDENT, "Failed to apply all modifications");
+
+            return success;
         }
 
         private async Task DownloadPackage(Package package)

Bloxstrap/Enums/CustomThemeTemplate.cs

@@ -0,0 +1,8 @@
+namespace Bloxstrap.Enums
+{
+    public enum CustomThemeTemplate
+    {
+        Blank,
+        Simple
+    }
+}

Bloxstrap/Exceptions/CustomThemeException.cs

@@ -0,0 +1,60 @@
+using Bloxstrap.Extensions;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Bloxstrap.Exceptions
+{
+    internal class CustomThemeException : Exception
+    {
+        /// <summary>
+        /// The exception message in English (for logging)
+        /// </summary>
+        public string EnglishMessage { get; } = null!;
+
+        public CustomThemeException(string translationString)
+            : base(Strings.ResourceManager.GetStringSafe(translationString))
+        {
+            EnglishMessage = Strings.ResourceManager.GetStringSafe(translationString, new CultureInfo("en-GB"));
+        }
+
+        public CustomThemeException(Exception innerException, string translationString)
+            : base(Strings.ResourceManager.GetStringSafe(translationString), innerException)
+        {
+            EnglishMessage = Strings.ResourceManager.GetStringSafe(translationString, new CultureInfo("en-GB"));
+        }
+
+        public CustomThemeException(string translationString, params object?[] args)
+            : base(string.Format(Strings.ResourceManager.GetStringSafe(translationString), args))
+        {
+            EnglishMessage = string.Format(Strings.ResourceManager.GetStringSafe(translationString, new CultureInfo("en-GB")), args);
+        }
+
+        public CustomThemeException(Exception innerException, string translationString, params object?[] args)
+            : base(string.Format(Strings.ResourceManager.GetStringSafe(translationString), args), innerException)
+        {
+            EnglishMessage = string.Format(Strings.ResourceManager.GetStringSafe(translationString, new CultureInfo("en-GB")), args);
+        }
+
+        public override string ToString()
+        {
+            StringBuilder sb = new StringBuilder(GetType().ToString());
+
+            if (!string.IsNullOrEmpty(Message))
+                sb.Append($": {Message}");
+
+            if (!string.IsNullOrEmpty(EnglishMessage) && Message != EnglishMessage)
+                sb.Append($" ({EnglishMessage})");
+
+            if (InnerException != null)
+                sb.Append($"\r\n ---> {InnerException}\r\n   ");
+
+            if (StackTrace != null)
+                sb.Append($"\r\n{StackTrace}");
+
+            return sb.ToString();
+        }
+    }
+}

Bloxstrap/Extensions/CustomThemeTemplateEx.cs

@@ -0,0 +1,10 @@
+namespace Bloxstrap.Extensions
+{
+    static class CustomThemeTemplateEx
+    {
+        public static string GetFileName(this CustomThemeTemplate template)
+        {
+            return $"CustomBootstrapperTemplate_{template}.xml";
+        }
+    }
+}

Bloxstrap/Models/APIs/Roblox/ClientVersion.cs

@@ -12,7 +12,5 @@
         public string BootstrapperVersion { get; set; } = null!;
 
         public DateTime? Timestamp { get; set; }
-
-        public bool IsBehindDefaultChannel { get; set; }
     }
 }

Bloxstrap/Resources/CustomBootstrapperTemplate_Blank.xml

@@ -1,4 +1,4 @@
-<BloxstrapCustomBootstrapper Version="0" Height="320" Width="500">
+<BloxstrapCustomBootstrapper Version="1" Height="320" Width="500">
 	<!-- Put UI elements here -->
 	<!-- Examples of custom bootstrappers can be found at https://github.com/bloxstraplabs/custom-bootstrapper-examples -->
 </BloxstrapCustomBootstrapper>

Bloxstrap/Resources/CustomBootstrapperTemplate_Simple.xml

@@ -0,0 +1,9 @@
+<BloxstrapCustomBootstrapper Version="1" Height="320" Width="520" IgnoreTitleBarInset="True" Theme="Default" Margin="30">
+	<!-- Find more custom bootstrapper examples at https://github.com/bloxstraplabs/custom-bootstrapper-examples -->
+	<TitleBar Title="" ShowMinimize="False" ShowClose="False" />
+
+	<Image Source="{Icon}" Height="100" Width="100" HorizontalAlignment="Center" Margin="0,15,0,0" />
+	<TextBlock HorizontalAlignment="Center" Name="StatusText" FontSize="20" Margin="0,170,0,0" />
+	<ProgressBar Width="450" Height="12" Name="PrimaryProgressBar" HorizontalAlignment="Center" Margin="0,200,0,0" />
+	<Button Content="Cancel" Name="CancelButton" HorizontalAlignment="Center" Margin="0,225,0,0" Height="30" Width="100" />
+</BloxstrapCustomBootstrapper>

Bloxstrap/Resources/Strings.Designer.cs

@@ -151,6 +151,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Roblox no longer supports Windows 7 or 8.1. To continue playing Roblox, please upgrade to Windows 10 or newer..
+        /// </summary>
+        public static string App_OSDeprecation_Win7_81 {
+            get {
+                return ResourceManager.GetString("App.OSDeprecation.Win7_81", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Bloxstrap was unable to automatically update to version {0}. Please update it manually by downloading and running it from the website..
         /// </summary>
@@ -169,6 +178,24 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Some content may be missing. Force a Roblox reinstallation in settings to fix this..
+        /// </summary>
+        public static string Bootstrapper_ExtractionFailed_Message {
+            get {
+                return ResourceManager.GetString("Bootstrapper.ExtractionFailed.Message", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to extract all files.
+        /// </summary>
+        public static string Bootstrapper_ExtractionFailed_Title {
+            get {
+                return ResourceManager.GetString("Bootstrapper.ExtractionFailed.Title", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Bloxstrap tried to upgrade Roblox but can&apos;t because Roblox&apos;s files are still in use.
         ///
@@ -198,6 +225,24 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Not all modifications will be present in the current launch..
+        /// </summary>
+        public static string Bootstrapper_ModificationsFailed_Message {
+            get {
+                return ResourceManager.GetString("Bootstrapper.ModificationsFailed.Message", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to apply all modifications.
+        /// </summary>
+        public static string Bootstrapper_ModificationsFailed_Title {
+            get {
+                return ResourceManager.GetString("Bootstrapper.ModificationsFailed.Title", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Bloxstrap does not have enough disk space to download and install Roblox. Please free up some disk space and try again..
         /// </summary>
@@ -396,6 +441,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Create New.
+        /// </summary>
+        public static string Common_CreateNew {
+            get {
+                return ResourceManager.GetString("Common.CreateNew", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Custom.
         /// </summary>
@@ -432,6 +486,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Edit.
+        /// </summary>
+        public static string Common_Edit {
+            get {
+                return ResourceManager.GetString("Common.Edit", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Export.
         /// </summary>
@@ -450,6 +513,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Import.
+        /// </summary>
+        public static string Common_Import {
+            get {
+                return ResourceManager.GetString("Common.Import", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Import from file.
         /// </summary>
@@ -585,6 +657,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Rename.
+        /// </summary>
+        public static string Common_Rename {
+            get {
+                return ResourceManager.GetString("Common.Rename", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Reset.
         /// </summary>
@@ -639,6 +720,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Template.
+        /// </summary>
+        public static string Common_Template {
+            get {
+                return ResourceManager.GetString("Common.Template", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Value.
         /// </summary>
@@ -802,6 +892,385 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to File must be a ZIP.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_FileNotZip {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.FileNotZip", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Name cannot be empty.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_NameEmpty {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.NameEmpty", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Name contains illegal characters.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_NameIllegalCharacters {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.NameIllegalCharacters", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Name cannot be used.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_NameReserved {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.NameReserved", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Name is already in use.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_NameTaken {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.NameTaken", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Unknown error.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_Unknown {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.Unknown", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Invalid or corrupted ZIP file.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_ZipInvalidData {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.ZipInvalidData", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Theme file could not be found in the ZIP file.
+        /// </summary>
+        public static string CustomTheme_Add_Errors_ZipMissingThemeFile {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Errors.ZipMissingThemeFile", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Add Custom Theme.
+        /// </summary>
+        public static string CustomTheme_Add_Title {
+            get {
+                return ResourceManager.GetString("CustomTheme.Add.Title", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Save changes to {0}?.
+        /// </summary>
+        public static string CustomTheme_Editor_ConfirmSave {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.ConfirmSave", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Open Theme Directory.
+        /// </summary>
+        public static string CustomTheme_Editor_OpenThemeDirectory {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.OpenThemeDirectory", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Preview.
+        /// </summary>
+        public static string CustomTheme_Editor_Preview {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.Preview", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Save.
+        /// </summary>
+        public static string CustomTheme_Editor_Save {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.Save", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to An error occurred while saving your theme..
+        /// </summary>
+        public static string CustomTheme_Editor_Save_Error {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.Save.Error", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Theme successfully saved!.
+        /// </summary>
+        public static string CustomTheme_Editor_Save_Success {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.Save.Success", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Editing &quot;{0}&quot;.
+        /// </summary>
+        public static string CustomTheme_Editor_Title {
+            get {
+                return ResourceManager.GetString("CustomTheme.Editor.Title", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Custom dialog has already been initialised.
+        /// </summary>
+        public static string CustomTheme_Errors_DialogAlreadyInitialised {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.DialogAlreadyInitialised", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0}.{1} uses blacklisted scheme {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeBlacklistedUriScheme {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeBlacklistedUriScheme", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} has invalid {1}: {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeConversionError {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeConversionError", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} {1} is not a valid {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeInvalidType {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeInvalidType", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Element {0} is missing the {1} attribute.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeMissing {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeMissing", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0}.{1} is missing it&apos;s child.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeMissingChild {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeMissingChild", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0}.{1} can only have one child.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeMultipleChildren {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeMultipleChildren", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} can only have one {1} defined.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeMultipleDefinitions {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeMultipleDefinitions", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} {1} must be larger than {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeMustBeLargerThanMin {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeMustBeLargerThanMin", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} {1} must be smaller than {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeMustBeSmallerThanMax {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeMustBeSmallerThanMax", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0}.{1} could not be parsed into a {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeParseError {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeParseError", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0}.{1} {2} is null.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementAttributeParseErrorNull {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementAttributeParseErrorNull", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} cannot have a child of {1}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementInvalidChild {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementInvalidChild", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} can only have one child.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementMultipleChildren {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementMultipleChildren", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} failed to create {1}: {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_ElementTypeCreationFailed {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.ElementTypeCreationFailed", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Theme XML root is not {0}.
+        /// </summary>
+        public static string CustomTheme_Errors_InvalidRoot {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.InvalidRoot", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to No custom theme selected.
+        /// </summary>
+        public static string CustomTheme_Errors_NoThemeSelected {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.NoThemeSelected", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to setup custom bootstrapper: {0}.
+        ///Defaulting to Fluent..
+        /// </summary>
+        public static string CustomTheme_Errors_SetupFailed {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.SetupFailed", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Custom bootstrappers can only have a maximum of {0} elements, got {1}..
+        /// </summary>
+        public static string CustomTheme_Errors_TooManyElements {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.TooManyElements", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Unknown element {0}.
+        /// </summary>
+        public static string CustomTheme_Errors_UnknownElement {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.UnknownElement", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} Unknown {1} {2}.
+        /// </summary>
+        public static string CustomTheme_Errors_UnknownEnumValue {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.UnknownEnumValue", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} version is not a number.
+        /// </summary>
+        public static string CustomTheme_Errors_VersionNotNumber {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.VersionNotNumber", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} version {1} is not recognised.
+        /// </summary>
+        public static string CustomTheme_Errors_VersionNotRecognised {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.VersionNotRecognised", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} version is not set.
+        /// </summary>
+        public static string CustomTheme_Errors_VersionNotSet {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.VersionNotSet", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to {0} version {1} is no longer supported.
+        /// </summary>
+        public static string CustomTheme_Errors_VersionNotSupported {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.VersionNotSupported", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to parse the theme file: {0}.
+        /// </summary>
+        public static string CustomTheme_Errors_XMLParseFailed {
+            get {
+                return ResourceManager.GetString("CustomTheme.Errors.XMLParseFailed", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Add Fast Flag.
         /// </summary>
@@ -1170,6 +1639,24 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Blank.
+        /// </summary>
+        public static string Enums_CustomThemeTemplate_Blank {
+            get {
+                return ResourceManager.GetString("Enums.CustomThemeTemplate.Blank", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Simple.
+        /// </summary>
+        public static string Enums_CustomThemeTemplate_Simple {
+            get {
+                return ResourceManager.GetString("Enums.CustomThemeTemplate.Simple", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Catmoji.
         /// </summary>
@@ -1923,6 +2410,33 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to delete custom theme {0}: {1}.
+        /// </summary>
+        public static string Menu_Appearance_CustomThemes_DeleteFailed {
+            get {
+                return ResourceManager.GetString("Menu.Appearance.CustomThemes.DeleteFailed", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to No custom theme selected..
+        /// </summary>
+        public static string Menu_Appearance_CustomThemes_NoneSelected {
+            get {
+                return ResourceManager.GetString("Menu.Appearance.CustomThemes.NoneSelected", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Failed to rename custom theme {0}: {1}.
+        /// </summary>
+        public static string Menu_Appearance_CustomThemes_RenameFailed {
+            get {
+                return ResourceManager.GetString("Menu.Appearance.CustomThemes.RenameFailed", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Configure how Bloxstrap should look..
         /// </summary>

Bloxstrap/Resources/Strings.resx

@@ -1270,7 +1270,179 @@ Please close any applications that may be using Roblox's files, and relaunch.</v
     <value>All Bloxstrap logs</value>
     <comment>Label that appears next to a checkbox</comment>
   </data>
+  <data name="App.OSDeprecation.Win7_81" xml:space="preserve">
+    <value>Roblox no longer supports Windows 7 or 8.1. To continue playing Roblox, please upgrade to Windows 10 or newer.</value>
+  </data>
+  <data name="Bootstrapper.ExtractionFailed.Title" xml:space="preserve">
+    <value>Failed to extract all files</value>
+  </data>
+  <data name="Bootstrapper.ExtractionFailed.Message" xml:space="preserve">
+    <value>Some content may be missing. Force a Roblox reinstallation in settings to fix this.</value>
+  </data>
+  <data name="Bootstrapper.ModificationsFailed.Title" xml:space="preserve">
+    <value>Failed to apply all modifications</value>
+  </data>
+  <data name="Bootstrapper.ModificationsFailed.Message" xml:space="preserve">
+    <value>Not all modifications will be present in the current launch.</value>
+  </data>
   <data name="Menu.About.Licenses.Apache" xml:space="preserve">
     <value>Apache License 2.0</value>
   </data>
+  <data name="Enums.CustomThemeTemplate.Blank" xml:space="preserve">
+    <value>Blank</value>
+  </data>
+  <data name="Enums.CustomThemeTemplate.Simple" xml:space="preserve">
+    <value>Simple</value>
+  </data>
+  <data name="CustomTheme.Errors.InvalidRoot" xml:space="preserve">
+    <value>Theme XML root is not {0}</value>
+  </data>
+  <data name="CustomTheme.Errors.DialogAlreadyInitialised" xml:space="preserve">
+    <value>Custom dialog has already been initialised</value>
+  </data>
+  <data name="CustomTheme.Errors.TooManyElements" xml:space="preserve">
+    <value>Custom bootstrappers can only have a maximum of {0} elements, got {1}.</value>
+  </data>
+  <data name="CustomTheme.Errors.VersionNotSet" xml:space="preserve">
+    <value>{0} version is not set</value>
+  </data>
+  <data name="CustomTheme.Errors.VersionNotNumber" xml:space="preserve">
+    <value>{0} version is not a number</value>
+  </data>
+  <data name="CustomTheme.Errors.VersionNotSupported" xml:space="preserve">
+    <value>{0} version {1} is no longer supported</value>
+  </data>
+  <data name="CustomTheme.Errors.VersionNotRecognised" xml:space="preserve">
+    <value>{0} version {1} is not recognised</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementInvalidChild" xml:space="preserve">
+    <value>{0} cannot have a child of {1}</value>
+  </data>
+  <data name="CustomTheme.Errors.UnknownElement" xml:space="preserve">
+    <value>Unknown element {0}</value>
+  </data>
+  <data name="CustomTheme.Errors.XMLParseFailed" xml:space="preserve">
+    <value>Failed to parse the theme file: {0}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeConversionError" xml:space="preserve">
+    <value>{0} has invalid {1}: {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeMissing" xml:space="preserve">
+    <value>Element {0} is missing the {1} attribute</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeInvalidType" xml:space="preserve">
+    <value>{0} {1} is not a valid {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeMustBeLargerThanMin" xml:space="preserve">
+    <value>{0} {1} must be larger than {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeMustBeSmallerThanMax" xml:space="preserve">
+    <value>{0} {1} must be smaller than {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.UnknownEnumValue" xml:space="preserve">
+    <value>{0} Unknown {1} {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeMultipleDefinitions" xml:space="preserve">
+    <value>{0} can only have one {1} defined</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeMultipleChildren" xml:space="preserve">
+    <value>{0}.{1} can only have one child</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementMultipleChildren" xml:space="preserve">
+    <value>{0} can only have one child</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeMissingChild" xml:space="preserve">
+    <value>{0}.{1} is missing it's child</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeParseError" xml:space="preserve">
+    <value>{0}.{1} could not be parsed into a {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeParseErrorNull" xml:space="preserve">
+    <value>{0}.{1} {2} is null</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementAttributeBlacklistedUriScheme" xml:space="preserve">
+    <value>{0}.{1} uses blacklisted scheme {2}</value>
+  </data>
+  <data name="CustomTheme.Errors.ElementTypeCreationFailed" xml:space="preserve">
+    <value>{0} failed to create {1}: {2}</value>
+  </data>
+  <data name="CustomTheme.Editor.Title" xml:space="preserve">
+    <value>Editing "{0}"</value>
+  </data>
+  <data name="CustomTheme.Editor.Save.Success" xml:space="preserve">
+    <value>Theme successfully saved!</value>
+  </data>
+  <data name="CustomTheme.Editor.Save.Error" xml:space="preserve">
+    <value>An error occurred while saving your theme.</value>
+  </data>
+  <data name="CustomTheme.Editor.ConfirmSave" xml:space="preserve">
+    <value>Save changes to {0}?</value>
+  </data>
+  <data name="CustomTheme.Editor.Save" xml:space="preserve">
+    <value>Save</value>
+  </data>
+  <data name="CustomTheme.Editor.Preview" xml:space="preserve">
+    <value>Preview</value>
+  </data>
+  <data name="CustomTheme.Editor.OpenThemeDirectory" xml:space="preserve">
+    <value>Open Theme Directory</value>
+  </data>
+  <data name="Common.CreateNew" xml:space="preserve">
+    <value>Create New</value>
+  </data>
+  <data name="Common.Import" xml:space="preserve">
+    <value>Import</value>
+  </data>
+  <data name="CustomTheme.Add.Title" xml:space="preserve">
+    <value>Add Custom Theme</value>
+  </data>
+  <data name="Common.Template" xml:space="preserve">
+    <value>Template</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.NameEmpty" xml:space="preserve">
+    <value>Name cannot be empty</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.NameIllegalCharacters" xml:space="preserve">
+    <value>Name contains illegal characters</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.NameReserved" xml:space="preserve">
+    <value>Name cannot be used</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.Unknown" xml:space="preserve">
+    <value>Unknown error</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.NameTaken" xml:space="preserve">
+    <value>Name is already in use</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.FileNotZip" xml:space="preserve">
+    <value>File must be a ZIP</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.ZipMissingThemeFile" xml:space="preserve">
+    <value>Theme file could not be found in the ZIP file</value>
+  </data>
+  <data name="CustomTheme.Add.Errors.ZipInvalidData" xml:space="preserve">
+    <value>Invalid or corrupted ZIP file</value>
+  </data>
+  <data name="CustomTheme.Errors.NoThemeSelected" xml:space="preserve">
+    <value>No custom theme selected</value>
+  </data>
+  <data name="CustomTheme.Errors.SetupFailed" xml:space="preserve">
+    <value>Failed to setup custom bootstrapper: {0}.
+Defaulting to Fluent.</value>
+  </data>
+  <data name="Menu.Appearance.CustomThemes.NoneSelected" xml:space="preserve">
+    <value>No custom theme selected.</value>
+  </data>
+  <data name="Common.Rename" xml:space="preserve">
+    <value>Rename</value>
+  </data>
+  <data name="Common.Edit" xml:space="preserve">
+    <value>Edit</value>
+  </data>
+  <data name="Menu.Appearance.CustomThemes.DeleteFailed" xml:space="preserve">
+    <value>Failed to delete custom theme {0}: {1}</value>
+  </data>
+  <data name="Menu.Appearance.CustomThemes.RenameFailed" xml:space="preserve">
+    <value>Failed to rename custom theme {0}: {1}</value>
+  </data>
 </root>

Bloxstrap/RobloxInterfaces/Deployment.cs

@@ -176,16 +176,15 @@
                     App.Logger.WriteLine(LOG_IDENT, "Failed to contact clientsettingscdn! Falling back to clientsettings...");
                     App.Logger.WriteException(LOG_IDENT, ex);
 
-                    clientVersion = await Http.GetJson<ClientVersion>("https://clientsettings.roblox.com" + path);
+                    try
-                }
+                    {
-
+                        clientVersion = await Http.GetJson<ClientVersion>("https://clientsettings.roblox.com" + path);
-                // check if channel is behind LIVE
+                    }
-                if (!isDefaultChannel)
+                    catch (HttpRequestException httpEx)
-                {
+                    when (!isDefaultChannel && BadChannelCodes.Contains(httpEx.StatusCode))
-                    var defaultClientVersion = await GetInfo(DefaultChannel);
+                    {
-
+                        throw new InvalidChannelException(httpEx.StatusCode);
-                    if (Utilities.CompareVersions(clientVersion.Version, defaultClientVersion.Version) == VersionComparison.LessThan)
+                    }
-                        clientVersion.IsBehindDefaultChannel = true;
                 }
 
                 ClientVersionCache[cacheKey] = clientVersion;

Bloxstrap/UI/Elements/Bootstrapper/CustomDialog.Converters.cs

@@ -1,6 +1,7 @@
 using System.ComponentModel;
 using System.Windows;
 using System.Windows.Media;
+using System.Xml;
 using System.Xml.Linq;
 
 namespace Bloxstrap.UI.Elements.Bootstrapper
@@ -37,7 +38,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             }
             catch (Exception ex)
             {
-                throw new Exception($"{xmlElement.Name} has invalid {attributeName}: {ex.Message}", ex);
+                throw new CustomThemeException(ex, "CustomTheme.Errors.ElementAttributeConversionError", xmlElement.Name, attributeName, ex.Message);
             }
         }
 
@@ -82,7 +83,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             }
             catch (Exception ex)
             {
-                throw new Exception($"{element.Name} has invalid {attributeName}: {ex.Message}", ex);
+                throw new CustomThemeException(ex, "CustomTheme.Errors.ElementAttributeConversionError", element.Name, attributeName, ex.Message);
             }
         }
     }

Bloxstrap/UI/Elements/Bootstrapper/CustomDialog.Creator.cs

@@ -5,7 +5,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
 {
     public partial class CustomDialog
     {
-        const int Version = 0;
+        const int Version = 1;
 
         private class DummyFrameworkElement : FrameworkElement { }
 
@@ -59,11 +59,11 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
         private static T HandleXml<T>(CustomDialog dialog, XElement xmlElement) where T : class
         {
             if (!_elementHandlerMap.ContainsKey(xmlElement.Name.ToString()))
-                throw new Exception($"Unknown element {xmlElement.Name}");
+                throw new CustomThemeException("CustomTheme.Errors.UnknownElement", xmlElement.Name);
 
             var element = _elementHandlerMap[xmlElement.Name.ToString()](dialog, xmlElement);
             if (element is not T)
-                throw new Exception($"{xmlElement.Parent!.Name} cannot have a child of {xmlElement.Name}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementInvalidChild", xmlElement.Parent!.Name, xmlElement.Name);
 
             return (T)element;
         }
@@ -78,19 +78,37 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                 dialog.ElementGrid.Children.Add(uiElement);
         }
 
+        private static void AssertThemeVersion(string? versionStr)
+        {
+            if (string.IsNullOrEmpty(versionStr))
+                throw new CustomThemeException("CustomTheme.Errors.VersionNotSet", "BloxstrapCustomBootstrapper");
+
+            if (!uint.TryParse(versionStr, out uint version))
+                throw new CustomThemeException("CustomTheme.Errors.VersionNotNumber", "BloxstrapCustomBootstrapper");
+
+            switch (version)
+            {
+                case Version:
+                    break;
+                case 0: // Themes made between Oct 19, 2024 to Mar 11, 2025 (on the feature/custom-bootstrappers branch)
+                    throw new CustomThemeException("CustomTheme.Errors.VersionNotSupported", "BloxstrapCustomBootstrapper", version);
+                default:
+                    throw new CustomThemeException("CustomTheme.Errors.VersionNotRecognised", "BloxstrapCustomBootstrapper", version);
+            }
+        }
+
         private void HandleXmlBase(XElement xml)
         {
             if (_initialised)
-                throw new Exception("Custom dialog has already been initialised");
+                throw new CustomThemeException("CustomTheme.Errors.DialogAlreadyInitialised");
 
             if (xml.Name != "BloxstrapCustomBootstrapper")
-                throw new Exception("XML root is not a BloxstrapCustomBootstrapper");
+                throw new CustomThemeException("CustomTheme.Errors.InvalidRoot", "BloxstrapCustomBootstrapper");
 
-            if (xml.Attribute("Version")?.Value != Version.ToString())
+            AssertThemeVersion(xml.Attribute("Version")?.Value);
-                throw new Exception("Unknown BloxstrapCustomBootstrapper version");
 
             if (xml.Descendants().Count() > MaxElements)
-                throw new Exception($"Custom bootstrappers can have a maximum of {MaxElements} elements");
+                throw new CustomThemeException("CustomTheme.Errors.TooManyElements", MaxElements, xml.Descendants().Count());
 
             _initialised = true;
 
@@ -116,7 +134,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             }
             catch (Exception ex)
             {
-                throw new Exception($"XML parse failed: {ex.Message}", ex);
+                throw new CustomThemeException(ex, "CustomTheme.Errors.XMLParseFailed", ex.Message);
             }
 
             HandleXmlBase(xml);

Bloxstrap/UI/Elements/Bootstrapper/CustomDialog.Elements.cs

@@ -150,7 +150,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                 }
                 catch (Exception ex)
                 {
-                    throw new Exception($"ImageBrush Failed to create BitmapImage: {ex.Message}", ex);
+                    throw new CustomThemeException(ex, "CustomTheme.Errors.ElementTypeCreationFailed", "Image", "BitmapImage", ex.Message);
                 }
 
                 imageBrush.ImageSource = bitmapImage;
@@ -217,7 +217,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
 
             var first = brushElement.FirstNode as XElement;
             if (first == null)
-                throw new Exception($"{xmlElement.Name} {name} is missing the brush");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMissingChild", xmlElement.Name, name);
 
             var brush = HandleXml<Brush>(dialog, first);
             uiElement.SetValue(dependencyProperty, brush);
@@ -620,7 +620,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                     }
                     catch (Exception ex)
                     {
-                        throw new Exception($"Image Failed to create BitmapImage: {ex.Message}", ex);
+                        throw new CustomThemeException(ex, "CustomTheme.Errors.ElementTypeCreationFailed", "Image", "BitmapImage", ex.Message);
                     }
 
                     image.Source = bitmapImage;
@@ -693,7 +693,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                 if (element.Name == "Grid.RowDefinitions")
                 {
                     if (rowsSet)
-                        throw new Exception("Grid can only have one RowDefinitions defined");
+                        throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMultipleDefinitions", "Grid", "RowDefinitions");
                     rowsSet = true;
 
                     HandleXmlElement_Grid_RowDefinitions(grid, dialog, element);
@@ -701,7 +701,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                 else if (element.Name == "Grid.ColumnDefinitions")
                 {
                     if (columnsSet)
-                        throw new Exception("Grid can only have one ColumnDefinitions defined");
+                        throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMultipleDefinitions", "Grid", "ColumnDefinitions");
                     columnsSet = true;
 
                     HandleXmlElement_Grid_ColumnDefinitions(grid, dialog, element);
@@ -760,7 +760,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             if (children.Any())
             {
                 if (children.Count() > 1)
-                    throw new Exception("Border can only have one child");
+                    throw new CustomThemeException("CustomTheme.Errors.ElementMultipleChildren", "Border");
 
                 border.Child = HandleXml<UIElement>(dialog, children.First());
             }

Bloxstrap/UI/Elements/Bootstrapper/CustomDialog.Utilities.cs

@@ -26,7 +26,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                 if (defaultValue != null)
                     return defaultValue;
 
-                throw new Exception($"Element {element.Name} is missing the {attributeName} attribute");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMissing", element.Name, attributeName);
             }
 
             return attribute.Value.ToString();
@@ -41,12 +41,12 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                 if (defaultValue != null)
                     return (T)defaultValue;
 
-                throw new Exception($"Element {element.Name} is missing the {attributeName} attribute");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMissing", element.Name, attributeName);
             }
 
             T? parsed = ConvertValue<T>(attribute.Value);
             if (parsed == null)
-                throw new Exception($"{element.Name} {attributeName} is not a valid {typeof(T).Name}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeInvalidType", element.Name, attributeName, typeof(T).Name);
 
             return (T)parsed;
         }
@@ -63,7 +63,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
 
             T? parsed = ConvertValue<T>(attribute.Value);
             if (parsed == null)
-                throw new Exception($"{element.Name} {attributeName} is not a valid {typeof(T).Name}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeInvalidType", element.Name, attributeName, typeof(T).Name);
 
             return (T)parsed;
         }
@@ -71,17 +71,17 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
         private static void ValidateXmlElement(string elementName, string attributeName, int value, int? min = null, int? max = null)
         {
             if (min != null && value < min)
-                throw new Exception($"{elementName} {attributeName} must be larger than {min}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMustBeLargerThanMin", elementName, attributeName, min);
             if (max != null && value > max)
-                throw new Exception($"{elementName} {attributeName} must be smaller than {max}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMustBeSmallerThanMax", elementName, attributeName, max);
         }
 
         private static void ValidateXmlElement(string elementName, string attributeName, double value, double? min = null, double? max = null)
         {
             if (min != null && value < min)
-                throw new Exception($"{elementName} {attributeName} must be larger than {min}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMustBeLargerThanMin", elementName, attributeName, min);
             if (max != null && value > max)
-                throw new Exception($"{elementName} {attributeName} must be smaller than {max}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMustBeSmallerThanMax", elementName, attributeName, max);
         }
 
         // You can't do numeric only generics in .NET 6. The feature is exclusive to .NET 7+.
@@ -136,7 +136,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                     return FontWeights.UltraBlack;
 
                 default:
-                    throw new Exception($"{element.Name} Unknown FontWeight {value}");
+                    throw new CustomThemeException("CustomTheme.Errors.UnknownEnumValue", element.Name, "FontWeight", value);
             }
         }
 
@@ -158,7 +158,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                     return FontStyles.Oblique;
 
                 default:
-                    throw new Exception($"{element.Name} Unknown FontStyle {value}");
+                    throw new CustomThemeException("CustomTheme.Errors.UnknownEnumValue", element.Name, "FontStyle", value);
             }
         }
 
@@ -183,7 +183,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
                     return TextDecorations.Underline;
 
                 default:
-                    throw new Exception($"{element.Name} Unknown TextDecorations {value}");
+                    throw new CustomThemeException("CustomTheme.Errors.UnknownEnumValue", element.Name, "TextDecorations", value);
             }
         }
 
@@ -205,6 +205,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             if (sourcePath == null)
                 return null;
 
+            // TODO: this is bad :(
             return sourcePath.Replace("theme://", $"{dialog.ThemeDir}\\");
         }
 
@@ -218,13 +219,13 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             path = GetFullPath(dialog, path)!;
 
             if (!Uri.TryCreate(path, UriKind.RelativeOrAbsolute, out Uri? result))
-                throw new Exception($"{xmlElement.Name} failed to parse {name} as Uri");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeParseError", xmlElement.Name, name, "Uri");
 
             if (result == null)
-                throw new Exception($"{xmlElement.Name} {name} Uri is null");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeParseErrorNull", xmlElement.Name, name, "Uri");
 
             if (result.Scheme != "file")
-                throw new Exception($"{xmlElement.Name} {name} uses blacklisted scheme {result.Scheme}");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeBlacklistedUriScheme", xmlElement.Name, name, result.Scheme);
 
             return new GetImageSourceDataResult { Uri = result };
         }
@@ -234,7 +235,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
             var contentAttr = xmlElement.Attribute("Content");
             var contentElement = xmlElement.Element($"{xmlElement.Name}.Content");
             if (contentAttr != null && contentElement != null)
-                throw new Exception($"{xmlElement.Name} can only have one Content defined");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMultipleDefinitions", xmlElement.Name, "Content");
 
             if (contentAttr != null)
                 return GetTranslatedText(contentAttr.Value);
@@ -244,11 +245,11 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
 
             var children = contentElement.Elements();
             if (children.Count() > 1)
-                throw new Exception($"{xmlElement.Name}.Content can only have one child");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMultipleChildren", xmlElement.Name, "Content");
 
             var first = contentElement.FirstNode as XElement;
             if (first == null)
-                throw new Exception($"{xmlElement.Name} Content is missing the content");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMissingChild", xmlElement.Name, "Content");
 
             var uiElement = HandleXml<UIElement>(dialog, first);
             return uiElement;
@@ -262,7 +263,7 @@ namespace Bloxstrap.UI.Elements.Bootstrapper
 
             var children = effectElement.Elements();
             if (children.Count() > 1)
-                throw new Exception($"{xmlElement.Name}.Effect can only have one child");
+                throw new CustomThemeException("CustomTheme.Errors.ElementAttributeMultipleChildren", xmlElement.Name, "Effect");
 
             var child = children.FirstOrDefault();
             if (child == null)

Bloxstrap/UI/Elements/Dialogs/AddCustomThemeDialog.xaml

@@ -0,0 +1,165 @@
+<base:WpfUiWindow
+    x:Class="Bloxstrap.UI.Elements.Dialogs.AddCustomThemeDialog"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:base="clr-namespace:Bloxstrap.UI.Elements.Base"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:local="clr-namespace:Bloxstrap.UI.Elements.Dialogs"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:resources="clr-namespace:Bloxstrap.Resources"
+    xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
+    xmlns:viewmodels="clr-namespace:Bloxstrap.UI.ViewModels.Dialogs"
+    Title="Add Custom Theme"
+    Width="480"
+    MinHeight="0"
+    d:DataContext="{d:DesignInstance viewmodels:AddCustomThemeViewModel,
+                                     IsDesignTimeCreatable=True}"
+    Background="{ui:ThemeResource ApplicationBackgroundBrush}"
+    ExtendsContentIntoTitleBar="True"
+    ResizeMode="NoResize"
+    SizeToContent="Height"
+    WindowStartupLocation="CenterScreen"
+    mc:Ignorable="d">
+    <Grid>
+        <Grid>
+            <Grid.RowDefinitions>
+                <RowDefinition Height="Auto" />
+                <RowDefinition Height="*" />
+                <RowDefinition Height="Auto" />
+            </Grid.RowDefinitions>
+
+            <ui:TitleBar
+                Title="{x:Static resources:Strings.CustomTheme_Add_Title}"
+                Grid.Row="0"
+                Grid.ColumnSpan="2"
+                Padding="8"
+                CanMaximize="False"
+                KeyboardNavigation.TabNavigation="None"
+                ShowMaximize="False"
+                ShowMinimize="False" />
+
+            <TabControl
+                x:Name="Tabs"
+                Grid.Row="1"
+                Margin="16"
+                SelectedIndex="{Binding Path=SelectedTab, Mode=TwoWay}">
+                <TabItem Header="{x:Static resources:Strings.Common_CreateNew}">
+                    <Grid Grid.Row="1" Margin="16">
+                        <Grid.RowDefinitions>
+                            <RowDefinition Height="Auto" />
+                            <RowDefinition Height="Auto" />
+                        </Grid.RowDefinitions>
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="Auto" />
+                            <ColumnDefinition Width="*" />
+                        </Grid.ColumnDefinitions>
+
+                        <Grid
+                            Grid.Row="0"
+                            Grid.ColumnSpan="2"
+                            Margin="0,0,0,12">
+                            <Grid.RowDefinitions>
+                                <RowDefinition Height="Auto" />
+                                <RowDefinition Height="Auto" />
+                            </Grid.RowDefinitions>
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition Width="Auto" />
+                                <ColumnDefinition Width="*" />
+                            </Grid.ColumnDefinitions>
+
+                            <TextBlock
+                                Grid.Row="0"
+                                Grid.Column="0"
+                                MinWidth="100"
+                                VerticalAlignment="Center"
+                                Text="{x:Static resources:Strings.Common_Name}" />
+                            <TextBox
+                                Grid.Row="0"
+                                Grid.Column="1"
+                                Text="{Binding Path=Name, Mode=TwoWay}" />
+
+                            <TextBlock
+                                Grid.Row="1"
+                                Grid.Column="1"
+                                Foreground="{DynamicResource SystemFillColorCriticalBrush}"
+                                Text="{Binding Path=NameError, Mode=OneWay}"
+                                TextAlignment="Center"
+                                TextWrapping="Wrap"
+                                Visibility="{Binding Path=NameErrorVisibility, Mode=OneWay}" />
+                        </Grid>
+
+                        <TextBlock
+                            Grid.Row="1"
+                            Grid.Column="0"
+                            MinWidth="100"
+                            VerticalAlignment="Center"
+                            Text="{x:Static resources:Strings.Common_Template}" />
+
+                        <ComboBox
+                            Grid.Row="1"
+                            Grid.Column="1"
+                            ItemsSource="{Binding Path=Templates, Mode=OneTime}"
+                            Text="{Binding Path=Template, Mode=TwoWay}">
+                            <ComboBox.ItemTemplate>
+                                <DataTemplate>
+                                    <TextBlock Text="{Binding Path=., Converter={StaticResource EnumNameConverter}}" />
+                                </DataTemplate>
+                            </ComboBox.ItemTemplate>
+                        </ComboBox>
+                    </Grid>
+                </TabItem>
+                <TabItem Header="{x:Static resources:Strings.Common_Import}">
+                    <Grid Margin="11">
+                        <Grid.RowDefinitions>
+                            <RowDefinition Height="*" />
+                            <RowDefinition Height="*" />
+                            <RowDefinition Height="*" />
+                        </Grid.RowDefinitions>
+                        <TextBlock
+                            Grid.Row="0"
+                            FontSize="14"
+                            Text="{Binding Path=FilePath}"
+                            TextAlignment="Center"
+                            TextWrapping="Wrap"
+                            Visibility="{Binding Path=FilePathVisibility}" />
+                        <ui:Button
+                            Grid.Row="1"
+                            Margin="4"
+                            HorizontalAlignment="Stretch"
+                            Click="OnImportButtonClicked"
+                            Content="{x:Static resources:Strings.Common_ImportFromFile}"
+                            Icon="DocumentArrowUp16" />
+                        <TextBlock
+                            Grid.Row="2"
+                            Foreground="{DynamicResource SystemFillColorCriticalBrush}"
+                            Text="{Binding Path=FileError}"
+                            TextAlignment="Center"
+                            TextWrapping="Wrap"
+                            Visibility="{Binding Path=FileErrorVisibility}" />
+                    </Grid>
+                </TabItem>
+            </TabControl>
+
+            <Border
+                Grid.Row="2"
+                Margin="0,10,0,0"
+                Padding="15"
+                Background="{ui:ThemeResource SolidBackgroundFillColorSecondaryBrush}">
+                <StackPanel
+                    HorizontalAlignment="Right"
+                    FlowDirection="LeftToRight"
+                    Orientation="Horizontal">
+                    <Button
+                        MinWidth="100"
+                        Click="OnOkButtonClicked"
+                        Content="{x:Static resources:Strings.Common_OK}" />
+                    <Button
+                        MinWidth="100"
+                        Margin="12,0,0,0"
+                        Content="{x:Static resources:Strings.Common_Cancel}"
+                        IsCancel="True" />
+                </StackPanel>
+            </Border>
+        </Grid>
+    </Grid>
+</base:WpfUiWindow>

Bloxstrap/UI/Elements/Dialogs/AddCustomThemeDialog.xaml.cs

@@ -0,0 +1,230 @@
+using Bloxstrap.UI.Elements.Base;
+using Bloxstrap.UI.ViewModels.Dialogs;
+using Microsoft.Win32;
+using System.IO.Compression;
+using System.Windows;
+
+namespace Bloxstrap.UI.Elements.Dialogs
+{
+    /// <summary>
+    /// Interaction logic for AddCustomThemeDialog.xaml
+    /// </summary>
+    public partial class AddCustomThemeDialog : WpfUiWindow
+    {
+        private const int CreateNewTabId = 0;
+        private const int ImportTabId = 1;
+
+        private readonly AddCustomThemeViewModel _viewModel;
+
+        public bool Created { get; private set; } = false;
+        public string ThemeName { get; private set; } = "";
+        public bool OpenEditor { get; private set; } = false;
+
+        public AddCustomThemeDialog()
+        {
+            _viewModel = new AddCustomThemeViewModel();
+            _viewModel.Name = GenerateRandomName();
+
+            DataContext = _viewModel;
+
+            InitializeComponent();
+        }
+
+        private static string GetThemePath(string name)
+        {
+            return Path.Combine(Paths.CustomThemes, name, "Theme.xml");
+        }
+
+        private static string GenerateRandomName()
+        {
+            int count = Directory.GetDirectories(Paths.CustomThemes).Count();
+
+            string name = $"Custom Theme {count + 1}";
+
+            // TODO: this sucks
+            if (File.Exists(GetThemePath(name)))
+                name += " " + Random.Shared.Next(1, 100000).ToString(); // easy
+
+            return name;
+        }
+
+        private static string GetUniqueName(string name)
+        {
+            const int maxTries = 100;
+
+            if (!File.Exists(GetThemePath(name)))
+                return name;
+
+            for (int i = 1; i <= maxTries; i++)
+            {
+                string newName = $"{name}_{i}";
+                if (!File.Exists(GetThemePath(newName)))
+                    return newName;
+            }
+
+            // last resort
+            return $"{name}_{Random.Shared.Next(maxTries+1, 1_000_000)}";
+        }
+
+        private static void CreateCustomTheme(string name, CustomThemeTemplate template)
+        {
+            string dir = Path.Combine(Paths.CustomThemes, name);
+
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, true);
+            Directory.CreateDirectory(dir);
+
+            string themeFilePath = Path.Combine(dir, "Theme.xml");
+
+            string templateContent = Encoding.UTF8.GetString(Resource.Get(template.GetFileName()).Result);
+
+            File.WriteAllText(themeFilePath, templateContent);
+        }
+
+        private bool ValidateCreateNew()
+        {
+            const string LOG_IDENT = "AddCustomThemeDialog::ValidateCreateNew";
+
+            if (string.IsNullOrEmpty(_viewModel.Name))
+            {
+                _viewModel.NameError = Strings.CustomTheme_Add_Errors_NameEmpty;
+                return false;
+            }
+
+            var validationResult = PathValidator.IsFileNameValid(_viewModel.Name);
+
+            if (validationResult != PathValidator.ValidationResult.Ok)
+            {
+                switch (validationResult)
+                {
+                    case PathValidator.ValidationResult.IllegalCharacter:
+                        _viewModel.NameError = Strings.CustomTheme_Add_Errors_NameIllegalCharacters;
+                        break;
+                    case PathValidator.ValidationResult.ReservedFileName:
+                        _viewModel.NameError = Strings.CustomTheme_Add_Errors_NameReserved;
+                        break;
+                    default:
+                        App.Logger.WriteLine(LOG_IDENT, $"Got unhandled PathValidator::ValidationResult {validationResult}");
+                        Debug.Assert(false);
+
+                        _viewModel.NameError = Strings.CustomTheme_Add_Errors_Unknown;
+                        break;
+                }
+
+                return false;
+            }
+
+            // better to check for the file instead of the directory so broken themes can be overwritten
+            string path = Path.Combine(Paths.CustomThemes, _viewModel.Name, "Theme.xml");
+            if (File.Exists(path))
+            {
+                _viewModel.NameError = Strings.CustomTheme_Add_Errors_NameTaken;
+                return false;
+            }    
+
+            return true;
+        }
+
+        private bool ValidateImport()
+        {
+            const string LOG_IDENT = "AddCustomThemeDialog::ValidateImport";
+
+            if (!_viewModel.FilePath.EndsWith(".zip"))
+            {
+                _viewModel.FileError = Strings.CustomTheme_Add_Errors_FileNotZip;
+                return false;
+            }
+
+            try
+            {
+                using var zipFile = ZipFile.OpenRead(_viewModel.FilePath);
+                var entries = zipFile.Entries;
+
+                bool foundThemeFile = false;
+
+                foreach (var entry in entries)
+                {
+                    if (entry.FullName == "Theme.xml")
+                    {
+                        foundThemeFile = true;
+                        break;
+                    }
+                }
+
+                if (!foundThemeFile)
+                {
+                    _viewModel.FileError = Strings.CustomTheme_Add_Errors_ZipMissingThemeFile;
+                    return false;
+                }
+
+                return true;
+            }
+            catch (InvalidDataException ex)
+            {
+                App.Logger.WriteLine(LOG_IDENT, "Got invalid data");
+                App.Logger.WriteException(LOG_IDENT, ex);
+
+                _viewModel.FileError = Strings.CustomTheme_Add_Errors_ZipInvalidData;
+                return false;
+            }
+        }
+
+        private void CreateNew()
+        {
+            if (!ValidateCreateNew())
+                return;
+
+            CreateCustomTheme(_viewModel.Name, _viewModel.Template);
+
+            Created = true;
+            ThemeName = _viewModel.Name;
+            OpenEditor = true;
+
+            Close();
+        }
+
+        private void Import()
+        {
+            if (!ValidateImport())
+                return;
+
+            string fileName = Path.GetFileNameWithoutExtension(_viewModel.FilePath);
+            string name = GetUniqueName(fileName);
+
+            string directory = Path.Combine(Paths.CustomThemes, name);
+            if (Directory.Exists(directory))
+                Directory.Delete(directory, true);
+            Directory.CreateDirectory(directory);
+
+            var fastZip = new ICSharpCode.SharpZipLib.Zip.FastZip();
+            fastZip.ExtractZip(_viewModel.FilePath, directory, null);
+
+            Created = true;
+            ThemeName = name;
+            OpenEditor = false;
+
+            Close();
+        }
+
+        private void OnOkButtonClicked(object sender, RoutedEventArgs e)
+        {
+            if (_viewModel.SelectedTab == CreateNewTabId)
+                CreateNew();
+            else
+                Import();
+        }
+
+        private void OnImportButtonClicked(object sender, RoutedEventArgs e)
+        {
+            var dialog = new OpenFileDialog
+            {
+                Filter = $"{Strings.FileTypes_ZipArchive}|*.zip"
+            };
+
+            if (dialog.ShowDialog() != true)
+                return;
+
+            _viewModel.FilePath = dialog.FileName;
+        }
+    }
+}

Bloxstrap/UI/Elements/Editor/BootstrapperEditorWindow.xaml

@@ -8,6 +8,7 @@
     xmlns:dmodels="clr-namespace:Bloxstrap.UI.ViewModels.Editor"
     xmlns:local="clr-namespace:Bloxstrap.UI.Elements.Editor"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:resources="clr-namespace:Bloxstrap.Resources"
     xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
     Title="{Binding Path=Title, Mode=OneTime}"
     Width="1000"
@@ -48,7 +49,7 @@
             Grid.Row="2"
             Margin="10"
             Command="{Binding Path=OpenThemeFolderCommand, Mode=OneTime}"
-            Content="Open Theme Folder" />
+            Content="{x:Static resources:Strings.CustomTheme_Editor_OpenThemeDirectory}" />
 
         <Grid
             Grid.Row="2"
@@ -63,14 +64,14 @@
                 Grid.Column="0"
                 Margin="0,0,4,0"
                 Command="{Binding Path=PreviewCommand, Mode=OneTime}"
-                Content="Preview" />
+                Content="{x:Static resources:Strings.CustomTheme_Editor_Preview}" />
 
             <ui:Button
                 Grid.Column="1"
                 Margin="4,0,0,0"
                 Appearance="Primary"
                 Command="{Binding Path=SaveCommand, Mode=OneTime}"
-                Content="Save" />
+                Content="{x:Static resources:Strings.CustomTheme_Editor_Save}" />
         </Grid>
 
         <ui:Snackbar

Bloxstrap/UI/Elements/Editor/BootstrapperEditorWindow.xaml.cs

@@ -147,7 +147,7 @@ namespace Bloxstrap.UI.Elements.Editor
             _viewModel.ThemeSavedCallback = ThemeSavedCallback;
             _viewModel.Directory = directory;
             _viewModel.Name = name;
-            _viewModel.Title = $"Editing \"{name}\"";
+            _viewModel.Title = string.Format(Strings.CustomTheme_Editor_Title, name);
             _viewModel.Code = themeContents;
 
             DataContext = _viewModel;
@@ -173,9 +173,9 @@ namespace Bloxstrap.UI.Elements.Editor
         private void ThemeSavedCallback(bool success, string message)
         {
             if (success)
-                Snackbar.Show("Settings saved!", message, Wpf.Ui.Common.SymbolRegular.CheckmarkCircle32, Wpf.Ui.Common.ControlAppearance.Success);
+                Snackbar.Show(Strings.CustomTheme_Editor_Save_Success, message, Wpf.Ui.Common.SymbolRegular.CheckmarkCircle32, Wpf.Ui.Common.ControlAppearance.Success);
             else
-                Snackbar.Show("Error", message, Wpf.Ui.Common.SymbolRegular.ErrorCircle24, Wpf.Ui.Common.ControlAppearance.Danger);
+                Snackbar.Show(Strings.CustomTheme_Editor_Save_Error, message, Wpf.Ui.Common.SymbolRegular.ErrorCircle24, Wpf.Ui.Common.ControlAppearance.Danger);
         }
 
         private static string ToCRLF(string text)
@@ -194,7 +194,7 @@ namespace Bloxstrap.UI.Elements.Editor
             if (!_viewModel.CodeChanged)
                 return;
 
-            var result = Frontend.ShowMessageBox($"Save changes to {_viewModel.Name}?", MessageBoxImage.Information, MessageBoxButton.YesNoCancel);
+            var result = Frontend.ShowMessageBox(string.Format(Strings.CustomTheme_Editor_ConfirmSave, _viewModel.Name), MessageBoxImage.Information, MessageBoxButton.YesNoCancel);
             if (result == MessageBoxResult.Cancel)
             {
                 e.Cancel = true;

Bloxstrap/UI/Elements/Settings/Pages/AppearancePage.xaml

@@ -95,16 +95,19 @@
                     </StackPanel.Style>
                     <TextBlock Text="{x:Static resources:Strings.Common_Name}" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
                     <ui:TextBox Margin="0,4,0,0" Text="{Binding SelectedCustomThemeName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
-                    <Grid Margin="0,4,0,0">
+                    <Grid Margin="0,8,0,0">
                         <Grid.ColumnDefinitions>
                             <ColumnDefinition Width="*" />
                             <ColumnDefinition Width="*" />
+                            <ColumnDefinition Width="*" />
                         </Grid.ColumnDefinitions>
-                        <ui:Button Grid.Column="0" Margin="0,0,2,0" Icon="Add28" Content="Rename" HorizontalAlignment="Stretch" Command="{Binding RenameCustomThemeCommand, Mode=OneTime}" />
+
-                        <ui:Button Grid.Column="1" Margin="2,0,0,0" Icon="Add28" Content="Edit" HorizontalAlignment="Stretch" Command="{Binding EditCustomThemeCommand, Mode=OneTime}" />
+                        <ui:Button Grid.Column="0" Margin="0,0,4,0" Icon="Edit28" Content="{x:Static resources:Strings.Common_Rename}" HorizontalAlignment="Stretch" Command="{Binding RenameCustomThemeCommand, Mode=OneTime}" />
+                        <ui:Button Grid.Column="1" Margin="4,0,4,0" Icon="DesktopEdit24" Content="{x:Static resources:Strings.Common_Edit}" HorizontalAlignment="Stretch" Command="{Binding EditCustomThemeCommand, Mode=OneTime}" />
+                        <ui:Button Grid.Column="2" Margin="4,0,0,0" Icon="ArrowExportRtl24" Content="{x:Static resources:Strings.Common_Export}" HorizontalAlignment="Stretch" Command="{Binding ExportCustomThemeCommand, Mode=OneTime}" />
                     </Grid>
                 </StackPanel>
-                <TextBlock Grid.Row="0" Grid.RowSpan="2" Grid.Column="1" Text="No custom theme selected." TextWrapping="Wrap" VerticalAlignment="Center" HorizontalAlignment="Center">
+                <TextBlock Grid.Row="0" Grid.RowSpan="2" Grid.Column="1" Text="{x:Static resources:Strings.Menu_Appearance_CustomThemes_NoneSelected}" TextWrapping="Wrap" VerticalAlignment="Center" HorizontalAlignment="Center">
                     <TextBlock.Style>
                         <Style>
                             <Style.Triggers>

Bloxstrap/UI/Frontend.cs

@@ -67,7 +67,7 @@ namespace Bloxstrap.UI
             try
             {
                 if (App.Settings.Prop.SelectedCustomTheme == null)
-                    throw new Exception("No custom theme selected");
+                    throw new CustomThemeException("CustomTheme.Errors.NoThemeSelected");
 
                 CustomDialog dialog = new CustomDialog();
                 dialog.ApplyCustomTheme(App.Settings.Prop.SelectedCustomTheme);
@@ -78,7 +78,7 @@ namespace Bloxstrap.UI
                 App.Logger.WriteException(LOG_IDENT, ex);
 
                 if (!App.LaunchSettings.QuietFlag.Active)
-                    Frontend.ShowMessageBox($"Failed to setup custom bootstrapper: {ex.Message}.\nDefaulting to Fluent.", MessageBoxImage.Error);
+                    ShowMessageBox(string.Format(Strings.CustomTheme_Errors_SetupFailed, ex.Message), MessageBoxImage.Error);
 
                 return GetBootstrapperDialog(BootstrapperStyle.FluentDialog);
             }
@@ -110,5 +110,17 @@ namespace Bloxstrap.UI
                 return messagebox.Result;
             }));
         }
+
+        public static void ShowBalloonTip(string title, string message, System.Windows.Forms.ToolTipIcon icon = System.Windows.Forms.ToolTipIcon.None, int timeout = 5)
+        {
+            var notifyIcon = new System.Windows.Forms.NotifyIcon
+            {
+                Icon = Properties.Resources.IconBloxstrap,
+                Text = App.ProjectName,
+                Visible = true
+            };
+
+            notifyIcon.ShowBalloonTip(timeout, title, message, icon);
+        }
     }
 }

Bloxstrap/UI/ViewModels/Dialogs/AddCustomThemeViewModel.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace Bloxstrap.UI.ViewModels.Dialogs
+{
+    internal class AddCustomThemeViewModel : NotifyPropertyChangedViewModel
+    {
+        public static CustomThemeTemplate[] Templates => Enum.GetValues<CustomThemeTemplate>();
+
+        public CustomThemeTemplate Template { get; set; } = CustomThemeTemplate.Simple;
+
+        public string Name { get; set; } = "";
+
+        private string _filePath = "";
+        public string FilePath
+        {
+            get => _filePath;
+            set
+            {
+                if (_filePath != value)
+                {
+                    _filePath = value;
+                    OnPropertyChanged(nameof(FilePath));
+                    OnPropertyChanged(nameof(FilePathVisibility));
+                }
+            }
+        }
+        public Visibility FilePathVisibility => string.IsNullOrEmpty(FilePath) ? Visibility.Collapsed : Visibility.Visible;
+
+        public int SelectedTab { get; set; } = 0;
+
+        private string _nameError = "";
+        public string NameError
+        {
+            get => _nameError;
+            set
+            {
+                if (_nameError != value)
+                {
+                    _nameError = value;
+                    OnPropertyChanged(nameof(NameError));
+                    OnPropertyChanged(nameof(NameErrorVisibility));
+                }
+            }
+        }
+        public Visibility NameErrorVisibility => string.IsNullOrEmpty(NameError) ? Visibility.Collapsed : Visibility.Visible;
+
+        private string _fileError = "";
+        public string FileError
+        {
+            get => _fileError;
+            set
+            {
+                if (_fileError != value)
+                {
+                    _fileError = value;
+                    OnPropertyChanged(nameof(FileError));
+                    OnPropertyChanged(nameof(FileErrorVisibility));
+                }
+            }
+        }
+        public Visibility FileErrorVisibility => string.IsNullOrEmpty(FileError) ? Visibility.Collapsed : Visibility.Visible;
+    }
+}

Bloxstrap/UI/ViewModels/Settings/AppearanceViewModel.cs

@@ -4,11 +4,13 @@ using System.Windows.Controls;
 using System.Windows.Input;
 
 using CommunityToolkit.Mvvm.Input;
+using ICSharpCode.SharpZipLib.Zip;
 
 using Microsoft.Win32;
 
 using Bloxstrap.UI.Elements.Settings;
 using Bloxstrap.UI.Elements.Editor;
+using Bloxstrap.UI.Elements.Dialogs;
 
 namespace Bloxstrap.UI.ViewModels.Settings
 {
@@ -23,6 +25,7 @@ namespace Bloxstrap.UI.ViewModels.Settings
         public ICommand DeleteCustomThemeCommand => new RelayCommand(DeleteCustomTheme);
         public ICommand RenameCustomThemeCommand => new RelayCommand(RenameCustomTheme);
         public ICommand EditCustomThemeCommand => new RelayCommand(EditCustomTheme);
+        public ICommand ExportCustomThemeCommand => new RelayCommand(ExportCustomTheme);
 
         private void PreviewBootstrapper()
         {
@@ -131,31 +134,6 @@ namespace Bloxstrap.UI.ViewModels.Settings
             }
         }
 
-        private string CreateCustomThemeName()
-        {
-            int count = Directory.GetDirectories(Paths.CustomThemes).Count();
-
-            string name = $"Custom Theme {count + 1}";
-
-            // TODO: this sucks
-            if (Directory.Exists(Path.Combine(Paths.CustomThemes, name))) // DUCK
-                name += " " + Random.Shared.Next(1, 100000).ToString(); // easy
-
-            return name;
-        }
-
-        private void CreateCustomThemeStructure(string name)
-        {
-            string dir = Path.Combine(Paths.CustomThemes, name);
-            Directory.CreateDirectory(dir);
-
-            string themeFilePath = Path.Combine(dir, "Theme.xml");
-
-            string templateContent = Encoding.UTF8.GetString(Resource.Get("CustomBootstrapperTemplate.xml").Result);
-
-            File.WriteAllText(themeFilePath, templateContent);
-        }
-
         private void DeleteCustomThemeStructure(string name)
         {
             string dir = Path.Combine(Paths.CustomThemes, name);
@@ -171,24 +149,20 @@ namespace Bloxstrap.UI.ViewModels.Settings
 
         private void AddCustomTheme()
         {
-            string name = CreateCustomThemeName();
+            var dialog = new AddCustomThemeDialog();
+            dialog.ShowDialog();
 
-            try
+            if (dialog.Created)
             {
-                CreateCustomThemeStructure(name);
+                CustomThemes.Add(dialog.ThemeName);
-            }
+                SelectedCustomThemeIndex = CustomThemes.Count - 1;
-            catch (Exception ex)
-            {
-                App.Logger.WriteException("AppearanceViewModel::AddCustomTheme", ex);
-                Frontend.ShowMessageBox($"Failed to create custom theme: {ex.Message}", MessageBoxImage.Error);
-                return;
-            }
 
-            CustomThemes.Add(name);
+                OnPropertyChanged(nameof(SelectedCustomThemeIndex));
-            SelectedCustomThemeIndex = CustomThemes.Count - 1;
+                OnPropertyChanged(nameof(IsCustomThemeSelected));
 
-            OnPropertyChanged(nameof(SelectedCustomThemeIndex));
+                if (dialog.OpenEditor)
-            OnPropertyChanged(nameof(IsCustomThemeSelected));
+                    EditCustomTheme();
+            }
         }
 
         private void DeleteCustomTheme()
@@ -203,7 +177,7 @@ namespace Bloxstrap.UI.ViewModels.Settings
             catch (Exception ex)
             {
                 App.Logger.WriteException("AppearanceViewModel::DeleteCustomTheme", ex);
-                Frontend.ShowMessageBox($"Failed to delete custom theme {SelectedCustomTheme}: {ex.Message}", MessageBoxImage.Error);
+                Frontend.ShowMessageBox(string.Format(Strings.Menu_Appearance_CustomThemes_DeleteFailed, SelectedCustomTheme, ex.Message), MessageBoxImage.Error);
                 return;
             }
 
@@ -233,7 +207,7 @@ namespace Bloxstrap.UI.ViewModels.Settings
             catch (Exception ex)
             {
                 App.Logger.WriteException("AppearanceViewModel::RenameCustomTheme", ex);
-                Frontend.ShowMessageBox($"Failed to rename custom theme {SelectedCustomTheme}: {ex.Message}", MessageBoxImage.Error);
+                Frontend.ShowMessageBox(string.Format(Strings.Menu_Appearance_CustomThemes_RenameFailed, SelectedCustomTheme, ex.Message), MessageBoxImage.Error);
                 return;
             }
 
@@ -252,6 +226,48 @@ namespace Bloxstrap.UI.ViewModels.Settings
             new BootstrapperEditorWindow(SelectedCustomTheme).ShowDialog();
         }
 
+        private void ExportCustomTheme()
+        {
+            if (SelectedCustomTheme is null)
+                return;
+
+            var dialog = new SaveFileDialog
+            {
+                FileName = $"{SelectedCustomTheme}.zip",
+                Filter = $"{Strings.FileTypes_ZipArchive}|*.zip"
+            };
+
+            if (dialog.ShowDialog() != true)
+                return;
+
+            string themeDir = Path.Combine(Paths.CustomThemes, SelectedCustomTheme);
+
+            using var memStream = new MemoryStream();
+            using var zipStream = new ZipOutputStream(memStream);
+
+            foreach (var filePath in Directory.EnumerateFiles(themeDir, "*.*", SearchOption.AllDirectories))
+            {
+                string relativePath = filePath[(themeDir.Length + 1)..];
+
+                var entry = new ZipEntry(relativePath);
+                entry.DateTime = DateTime.Now;
+
+                zipStream.PutNextEntry(entry);
+
+                using var fileStream = File.OpenRead(filePath);
+                fileStream.CopyTo(zipStream);
+            }
+
+            zipStream.CloseEntry();
+            zipStream.Finish();
+            memStream.Position = 0;
+
+            using var outputStream = File.OpenWrite(dialog.FileName);
+            memStream.CopyTo(outputStream);
+
+            Process.Start("explorer.exe", $"/select,\"{dialog.FileName}\"");
+        }
+
         private void PopulateCustomThemes()
         {
             string? selected = App.Settings.Prop.SelectedCustomTheme;

Bloxstrap/Utility/Filesystem.cs

@@ -31,5 +31,15 @@ namespace Bloxstrap.Utility
             fileInfo.IsReadOnly = false;
             App.Logger.WriteLine("Filesystem::AssertReadOnly", $"The following file was set as read-only: {filePath}");
         }
+
+        internal static void AssertReadOnlyDirectory(string directoryPath)
+        {
+            var directory = new DirectoryInfo(directoryPath) { Attributes = FileAttributes.Normal };
+
+            foreach (var info in directory.GetFileSystemInfos("*", SearchOption.AllDirectories))
+                info.Attributes = FileAttributes.Normal;
+
+            App.Logger.WriteLine("Filesystem::AssertReadOnlyDirectory", $"The following directory was set as read-only: {directoryPath}");
+        }
     }
 }

Bloxstrap/Utility/PathValidator.cs

@@ -0,0 +1,104 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Bloxstrap.Utility
+{
+    internal static class PathValidator
+    {
+        public enum ValidationResult
+        {
+            Ok,
+            IllegalCharacter,
+            ReservedFileName,
+            ReservedDirectoryName
+        }
+
+        private static readonly string[] _reservedNames = new string[]
+        {
+            "CON",
+            "PRN",
+            "AUX",
+            "NUL",
+            "COM1",
+            "COM2",
+            "COM3",
+            "COM4",
+            "COM5",
+            "COM6",
+            "COM7",
+            "COM8",
+            "COM9",
+            "LPT1",
+            "LPT2",
+            "LPT3",
+            "LPT4",
+            "LPT5",
+            "LPT6",
+            "LPT7",
+            "LPT8",
+            "LPT9"
+        };
+
+        private static readonly char[] _directorySeperatorDelimiters = new char[]
+        {
+            Path.DirectorySeparatorChar,
+            Path.AltDirectorySeparatorChar
+        };
+
+        private static readonly char[] _invalidPathChars = GetInvalidPathChars();
+
+        public static char[] GetInvalidPathChars()
+        {
+            char[] invalids = new char[] { '/', '\\', ':', '*', '?', '"', '<', '>', '|' };
+            char[] otherInvalids = Path.GetInvalidPathChars();
+
+            char[] result = new char[invalids.Length + otherInvalids.Length];
+            invalids.CopyTo(result, 0);
+            otherInvalids.CopyTo(result, invalids.Length);
+
+            return result;
+        }
+
+        public static ValidationResult IsFileNameValid(string fileName)
+        {
+            if (fileName.IndexOfAny(_invalidPathChars) != -1)
+                return ValidationResult.IllegalCharacter;
+
+            string fileNameNoExt = Path.GetFileNameWithoutExtension(fileName).ToUpperInvariant();
+            if (_reservedNames.Contains(fileNameNoExt))
+                return ValidationResult.ReservedFileName;
+
+            return ValidationResult.Ok;
+        }
+
+        public static ValidationResult IsPathValid(string path)
+        {
+            string? pathRoot = Path.GetPathRoot(path);
+            string pathNoRoot = pathRoot != null ? path[pathRoot.Length..] : path;
+
+            string[] pathParts = pathNoRoot.Split(_directorySeperatorDelimiters);
+
+            foreach (var part in pathParts)
+            {
+                if (part.IndexOfAny(_invalidPathChars) != -1)
+                    return ValidationResult.IllegalCharacter;
+
+                if (_reservedNames.Contains(part))
+                    return ValidationResult.ReservedDirectoryName;
+            }
+
+            string fileName = Path.GetFileName(path);
+            if (fileName.IndexOfAny(_invalidPathChars) != -1)
+                return ValidationResult.IllegalCharacter;
+
+            string fileNameNoExt = Path.GetFileNameWithoutExtension(path).ToUpperInvariant();
+            if (_reservedNames.Contains(fileNameNoExt))
+                return ValidationResult.ReservedFileName;
+
+            return ValidationResult.Ok;
+        }
+    }
+}