MacOS app: Customize window appearance and maximize on API selection

Author: MikhailGorobets

NativeApp/Apple/Source/Classes/OSX/AppDelegate.m

@@ -17,6 +17,9 @@ @implementation AppDelegate
 - (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
     NSWindow* mainWindow = [[NSApplication sharedApplication]mainWindow];
     [mainWindow setAcceptsMouseMovedEvents:YES];
+
+    // Force dark appearance for the entire application
+    [NSApp setAppearance:[NSAppearance appearanceNamed:NSAppearanceNameDarkAqua]];
 }
 
 - (void)applicationWillTerminate:(NSNotification *)aNotification {

NativeApp/Apple/Source/Classes/OSX/ModeSelectionViewController.mm

@@ -33,10 +33,19 @@ @implementation ModeSelectionViewController
 {
 }
 
-- (void) setWindowTitle:(NSString*) title
+- (void) setWindowTitle:(NSString*) title forWindow:(NSWindow*) window
 {
-    NSWindow* mainWindow = [[NSApplication sharedApplication]mainWindow];
-    [mainWindow setTitle:title];
+    [window setTitle:title];
+}
+
+- (void) maximizeWindow:(NSWindow*)window
+{
+    if (window)
+    {
+        // Fill the entire visible screen area (excluding Dock and menu bar)
+        NSRect screenFrame = window.screen.visibleFrame;
+        [window setFrame:screenFrame display:YES animate:YES];
+    }
 }
 
 - (void)viewDidLoad
@@ -97,8 +106,9 @@ - (void) terminateApp:(NSString*) error
 
 - (IBAction)goOpenGL:(id)sender
 {
+    NSWindow* window = self.view.window;
     ViewController* glViewController = [self.storyboard instantiateControllerWithIdentifier:@"GLViewControllerID"];
-    self.view.window.contentViewController = glViewController;
+    window.contentViewController = glViewController;
 
     GLView* glView = (GLView*)[glViewController view];
     NSString* error = [glView getError];
@@ -108,13 +118,15 @@ - (IBAction)goOpenGL:(id)sender
     }
 
     NSString* name =  [glView getAppName];
-    [self setWindowTitle:name];
+    [self setWindowTitle:name forWindow:window];
+    [self maximizeWindow:window];
 }
 
 - (IBAction)goVulkan:(id)sender
 {
+    NSWindow* window = self.view.window;
     ViewController* metalViewController = [self.storyboard instantiateControllerWithIdentifier:@"MoltenVKViewControllerID"];
-    self.view.window.contentViewController = metalViewController;
+    window.contentViewController = metalViewController;
 
     MetalView* mtlView = (MetalView*)[metalViewController view];
     NSString* error = [mtlView getError];
@@ -124,14 +136,16 @@ - (IBAction)goVulkan:(id)sender
     }
 
     NSString* name =  [mtlView getAppName];
-    [self setWindowTitle:name];
+    [self setWindowTitle:name forWindow:window];
+    [self maximizeWindow:window];
 }
 
 - (IBAction)goMetal:(id)sender
 {
+    NSWindow* window = self.view.window;
     ViewController* metalViewController = [self.storyboard instantiateControllerWithIdentifier:@"MetalViewControllerID"];
     MetalView* mtlView = (MetalView*)[metalViewController view];
-    self.view.window.contentViewController = metalViewController;
+    window.contentViewController = metalViewController;
 
     NSString* error = [mtlView getError];
     if(error != nil)
@@ -140,14 +154,16 @@ - (IBAction)goMetal:(id)sender
     }
 
     NSString* name =  [mtlView getAppName];
-    [self setWindowTitle:name];
+    [self setWindowTitle:name forWindow:window];
+    [self maximizeWindow:window];
 }
 
 - (IBAction)goWebGPU:(id)sender
 {
+    NSWindow* window = self.view.window;
     ViewController* webgpuViewController = [self.storyboard instantiateControllerWithIdentifier:@"WebGPUViewControllerID"];
     WebGPUView* webgpuView = (WebGPUView*)[webgpuViewController view];
-    self.view.window.contentViewController = webgpuViewController;
+    window.contentViewController = webgpuViewController;
 
     NSString* error = [webgpuView getError];
     if(error != nil)
@@ -156,7 +172,8 @@ - (IBAction)goWebGPU:(id)sender
     }
 
     NSString* name = [webgpuView getAppName];
-    [self setWindowTitle:name];
+    [self setWindowTitle:name forWindow:window];
+    [self maximizeWindow:window];
 }
 
 @end

NativeApp/Apple/Source/Classes/OSX/WindowController.mm

@@ -40,6 +40,25 @@ - (instancetype)initWithWindow:(NSWindow *)window
     return self;
 }
 
+- (void)windowDidLoad
+{
+    [super windowDidLoad];
+
+    NSWindow* window = self.window;
+
+    // Force dark appearance to match the application UI
+    window.appearance = [NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
+
+    // Make the titlebar transparent so it blends with the window background
+    window.titlebarAppearsTransparent = YES;
+
+    // Set window background color matching ImGuiColors::TitleBg (~0.07, 0.08, 0.11)
+    window.backgroundColor = [NSColor colorWithRed:0.07 green:0.08 blue:0.11 alpha:1.0];
+
+    // Hide the title text (the app name is shown in the content area)
+    window.titleVisibility = NSWindowTitleHidden;
+}
+
 - (void) goFullscreen
 {
     // If app is already fullscreen...