Add support for multi-instance launching (#72)

didnt fully look into handling mutex ownership and it'll probably screw up when the first roblox window is closed so hopefully this works fine 👍

Bloxstrap/Bootstrapper.cs

@@ -5,6 +5,7 @@ using System.IO;
 using System.IO.Compression;
 using System.Linq;
 using System.Net.Http;
+using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 using System.Windows;
@@ -232,20 +233,21 @@ namespace Bloxstrap
 
             LaunchCommandLine  += " -startEvent " + startEventName;
 
-            using (SystemEvent startEvent = new(startEventName))
-            {
             bool shouldWait = false;
-
             Process gameClient = Process.Start(Path.Combine(VersionFolder, "RobloxPlayerBeta.exe"), LaunchCommandLine);
             Process? rbxFpsUnlocker = null;
             DiscordRichPresence? richPresence = null;
+            Mutex? singletonMutex = null;
 
+            using (SystemEvent startEvent = new(startEventName))
+            {
                 bool startEventFired = await startEvent.WaitForEvent();
 
                 startEvent.Close();
 
                 if (!startEventFired)
                     return;
+            }
             
             if (App.Settings.RFUEnabled && Process.GetProcessesByName("rbxfpsunlocker").Length == 0) 
             { 
@@ -261,15 +263,19 @@ namespace Bloxstrap
                     shouldWait = true;
             }
 
+            if (App.Settings.MultiInstanceLaunching)
+            {
+                singletonMutex = new Mutex(true, "ROBLOX_singletonMutex");
+                shouldWait = true;
+            }
+
             // event fired, wait for 3 seconds then close
             await Task.Delay(3000);
 
-                // now we move onto handling rich presence
             if (App.Settings.UseDiscordRichPresence)
             {
                 richPresence = new DiscordRichPresence();
                 richPresence.MonitorGameActivity();
-
                 shouldWait = true;
             }
 
@@ -281,11 +287,11 @@ namespace Bloxstrap
             await gameClient.WaitForExitAsync();
 
             richPresence?.Dispose();
+            singletonMutex?.ReleaseMutex();
 
             if (App.Settings.RFUAutoclose && rbxFpsUnlocker is not null)
                 rbxFpsUnlocker.Kill();
         }
-        }
 
         public void CancelButtonClicked()
         {

Bloxstrap/Models/SettingsFormat.cs

@@ -20,6 +20,7 @@ namespace Bloxstrap.Models
         public Theme Theme { get; set; } = Theme.Default;
         public bool CheckForUpdates { get; set; } = true;
         public bool CreateDesktopIcon { get; set; } = true;
+        public bool MultiInstanceLaunching { get; set; } = false;
 
         // channel configuration
         public string Channel { get; set; } = DeployManager.DefaultChannel;

Bloxstrap/ViewModels/BootstrapperViewModel.cs

@@ -39,6 +39,12 @@ namespace Bloxstrap.ViewModels
             set => App.Settings.PromptChannelChange = value;
         }
 
+        public bool MultiInstanceLaunchingEnabled
+        {
+            get => App.Settings.MultiInstanceLaunching;
+            set => App.Settings.MultiInstanceLaunching = value;
+        }
+
         public IReadOnlyDictionary<string, Theme> Themes { get; set; } = new Dictionary<string, Theme>()
         {
             { "System Default", Enums.Theme.Default },

Bloxstrap/Views/Pages/BootstrapperPage.xaml

@@ -23,6 +23,15 @@
             </ui:CardControl.Header>
             <ui:ToggleSwitch IsChecked="{Binding UpdateCheckingEnabled, Mode=TwoWay}" />
         </ui:CardControl>
+        <ui:CardControl Margin="0,8,0,0">
+            <ui:CardControl.Header>
+                <StackPanel Grid.Column="0">
+                    <TextBlock FontSize="13" FontWeight="Medium" Text="Allow multi-game instance launching" />
+                    <TextBlock FontSize="12" Text="Roblox will allow having more than one game instance open simultaneously." Foreground="{DynamicResource TextFillColorTertiaryBrush}" />
+                </StackPanel>
+            </ui:CardControl.Header>
+            <ui:ToggleSwitch IsChecked="{Binding MultiInstanceLaunchingEnabled, Mode=TwoWay}" />
+        </ui:CardControl>
         <ui:CardControl Margin="0,8,0,0">
             <ui:CardControl.Header>
                 <StackPanel Grid.Column="0">