Fix UseNativeWindowSystem option to be Windows-only

Source/Editor/GUI/MainMenu.cs

@@ -61,7 +61,9 @@ namespace FlaxEditor.GUI
         public MainMenu(RootControl mainWindow)
         : base(0, 0, 0, 20)
         {
+#if PLATFORM_WINDOWS
             _useCustomWindowSystem = !Editor.Instance.Options.Options.Interface.UseNativeWindowSystem;
+#endif
             AutoFocus = false;
             AnchorPreset = AnchorPresets.HorizontalStretchTop;
 

Source/Editor/GUI/MainMenuButton.cs

@@ -42,12 +42,14 @@ namespace FlaxEditor.GUI
             Text = text;
 
             var style = Style.Current;
+#if PLATFORM_WINDOWS
             if (Editor.Instance.Options.Options.Interface.UseNativeWindowSystem)
             {
                 BackgroundColorMouseOver = style.BackgroundHighlighted;
                 BackgroundColorMouseOverOpened = style.Background;
             }
             else
+#endif
             {
                 BackgroundColorMouseOver = BackgroundColorMouseOverOpened = style.LightBackground * 1.3f;
             }

Source/Editor/Modules/UIModule.cs

@@ -296,7 +296,9 @@ namespace FlaxEditor.Modules
             InitDockPanel(mainWindow);
 
             // Add dummy control for drawing the main window borders if using a custom style
+#if PLATFORM_WINDOWS
             if (!Editor.Options.Options.Interface.UseNativeWindowSystem)
+#endif
             {
                 mainWindow.AddChild(new CustomWindowBorderControl
                 {

Source/Editor/Modules/WindowsModule.cs

@@ -712,7 +712,9 @@ namespace FlaxEditor.Modules
             settings.Size = new Vector2(1300 * dpiScale, 900 * dpiScale);
             settings.StartPosition = WindowStartPosition.CenterScreen;
 
+#if PLATFORM_WINDOWS
             if (!Editor.Instance.Options.Options.Interface.UseNativeWindowSystem)
+#endif
             {
                 settings.HasBorder = false;
                 settings.HasSizingFrame = false;

Source/Editor/Options/InterfaceOptions.cs

@@ -44,6 +44,8 @@ namespace FlaxEditor.Options
         [EditorDisplay("Interface"), EditorOrder(10), Tooltip("Editor User Interface scale. Applied to all UI elements, windows and text. Can be used to scale the interface up on a bigger display. Editor restart required.")]
         public float InterfaceScale { get; set; } = 1.0f;
 
+#if PLATFORM_WINDOWS
+
         /// <summary>
         /// Gets or sets a value indicating whether use native window title bar. Editor restart required.
         /// </summary>
@@ -51,6 +53,8 @@ namespace FlaxEditor.Options
         [EditorDisplay("Interface"), EditorOrder(70), Tooltip("Determines whether use native window title bar. Editor restart required.")]
         public bool UseNativeWindowSystem { get; set; } = false;
 
+#endif
+
         /// <summary>
         /// Gets or sets a value indicating whether show selected camera preview in the editor window.
         /// </summary>