remove server side decorations FIXME and document why its needed

Signed-off-by: Jan200101 <sentrycraft123@gmail.com>

launcher/ui/MainWindow.cpp

@@ -231,7 +231,8 @@ MainWindow::MainWindow(QWidget* parent) : QMainWindow(parent), ui(new Ui::MainWi
         setInstanceActionsEnabled(false);
 
         // add a close button at the end of the main toolbar when running on gamescope / steam deck
-        // FIXME: detect if we don't have server side decorations instead
+        // this is only needed on gamescope because it defaults to an X11/XWayland session and
+        // does not implement decorations
         if (qgetenv("XDG_CURRENT_DESKTOP") == "gamescope") {
             ui->mainToolBar->addAction(ui->actionCloseWindow);
         }