macOS: Fix changes to macos_titlebar_color while in full screen not being applied after exiting fullscreen

Fixes #9350

docs/changelog.rst

@@ -163,6 +163,9 @@ Detailed list of changes
 - Fix a regression that broke using line numbers with the edit-in-kitty command
   (:pull:`9346`)
 
+- macOS: Fix changes to :opt:`macos_titlebar_color` while in full screen not being applied after exiting fullscreen (:iss:`9350`)
+
+
 0.45.0 [2025-12-24]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

glfw/cocoa_platform.h

@@ -139,6 +139,9 @@ typedef struct _GLFWwindowNS
     float           xscale, yscale;
     int             blur_radius;
     bool live_resize_in_progress;
+    struct {
+        struct { CGFloat red, green, blue, alpha; bool was_set; } color; bool transparent;
+    } last_applied_titlebar_settings;
 
     // The total sum of the distances the cursor has been warped
     // since the last cursor motion event was processed

glfw/cocoa_window.m

@@ -1712,6 +1712,8 @@ void _glfwPlatformUpdateIMEState(_GLFWwindow *w, const GLFWIMEUpdateEvent *ev) {
     return !glfw_window->ns.layer_shell.is_active || glfw_window->ns.layer_shell.config.type != GLFW_LAYER_SHELL_BACKGROUND;
 }
 
+static void apply_titlebar_color_settings(_GLFWwindow *window);
+
 static void
 update_titlebar_button_visibility_after_fullscreen_transition(_GLFWwindow* w, bool traditional, bool made_fullscreen) {
     // Update window button visibility
@@ -1728,6 +1730,7 @@ update_titlebar_button_visibility_after_fullscreen_transition(_GLFWwindow* w, bo
         [[window standardWindowButton: NSWindowMiniaturizeButton] setHidden:button_hidden];
         [[window standardWindowButton: NSWindowZoomButton] setHidden:button_hidden];
     }
+    if (!made_fullscreen) apply_titlebar_color_settings(w);
 }
 
 - (void)toggleFullScreen:(nullable id)sender
@@ -3346,6 +3349,20 @@ set_title_bar_background(NSWindow *window, NSColor *backgroundColor) {
 #undef tag
 }
 
+static void
+apply_titlebar_color_settings(_GLFWwindow *window) {
+#define tc window->ns.last_applied_titlebar_settings.color
+    GLFWWindow *nsw = window->ns.object;
+    if (!window->ns.titlebar_hidden && window->decorated && tc.was_set && window->ns.last_applied_titlebar_settings.transparent) {
+        NSColor *titlebar_color = [NSColor colorWithSRGBRed:tc.red green:tc.green blue:tc.blue alpha:tc.alpha];
+        set_title_bar_background(nsw, titlebar_color);
+        [titlebar_color release];
+    } else clear_title_bar_background_views(nsw);
+#undef tc
+}
+
+
+
 GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool use_system_color, unsigned int system_color, int background_blur, unsigned int hide_window_decorations, bool show_text_in_titlebar, int color_space, float background_opacity, bool resizable) { @autoreleasepool {
     _GLFWwindow* window = (_GLFWwindow*)w;
     if (window->ns.layer_shell.is_active) return;
@@ -3359,8 +3376,9 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
         window_background = background_blur > 0 ? [NSColor colorWithWhite: 0 alpha: 0.001f] : [NSColor clearColor];
     }
     NSAppearance *appearance = nil;
-    bool titlebar_transparent = false;
+#define tc window->ns.last_applied_titlebar_settings.color
-    NSColor *titlebar_color = nil;
+    tc.was_set = false;
+    window->ns.last_applied_titlebar_settings.transparent = false;
     const NSWindowStyleMask current_style_mask = [nsw styleMask];
     const bool in_fullscreen = ((current_style_mask & NSWindowStyleMaskFullScreen) != 0) || window->ns.in_traditional_fullscreen;
     NSAppearance *light_appearance = is_transparent ? [NSAppearance appearanceNamed:NSAppearanceNameVibrantLight] : [NSAppearance appearanceNamed:NSAppearanceNameAqua];
@@ -3373,13 +3391,14 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
                 appearance = dark_appearance; break;
         }
     } else {
-        double red = ((color >> 16) & 0xFF) / 255.0;
+        tc.red = ((color >> 16) & 0xFF) / 255.0;
-        double green = ((color >> 8) & 0xFF) / 255.0;
+        tc.green = ((color >> 8) & 0xFF) / 255.0;
-        double blue = (color & 0xFF) / 255.0;
+        tc.blue = (color & 0xFF) / 255.0;
-        double luma = 0.2126 * red + 0.7152 * green + 0.0722 * blue;
+        tc.alpha = background_opacity;
+        tc.was_set = true;
+        double luma = 0.2126 * tc.red + 0.7152 * tc.green + 0.0722 * tc.blue;
         appearance = luma < 0.5 ? dark_appearance : light_appearance;
-        titlebar_color = [NSColor colorWithSRGBRed:red green:green blue:blue alpha:background_opacity];
+        window->ns.last_applied_titlebar_settings.transparent = true;
-        titlebar_transparent = true;
     }
     [nsw setBackgroundColor:window_background];
     [nsw setAppearance:appearance];
@@ -3396,7 +3415,7 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
             decorations_desc = "no-titlebar";
             window->decorated = true;
             has_shadow = true;
-            titlebar_transparent = true;
+            window->ns.last_applied_titlebar_settings.transparent = true;
             window->ns.titlebar_hidden = true;
             show_text_in_titlebar = false;
             break;
@@ -3414,7 +3433,7 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
     // https://github.com/kovidgoyal/kitty/issues/6439
     if (is_transparent) has_shadow = false;
     bool hide_titlebar_buttons = !in_fullscreen && window->ns.titlebar_hidden;
-    [nsw setTitlebarAppearsTransparent:titlebar_transparent];
+    [nsw setTitlebarAppearsTransparent:window->ns.last_applied_titlebar_settings.transparent];
     [nsw setHasShadow:has_shadow];
     [nsw setTitleVisibility:(show_text_in_titlebar) ? NSWindowTitleVisible : NSWindowTitleHidden];
     NSColorSpace *cs = nil;
@@ -3427,13 +3446,13 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
     debug(
         "Window Chrome state:\n\tbackground: %s\n\tappearance: %s color_space: %s\n\t"
         "blur: %d has_shadow: %d resizable: %d decorations: %s (%d)\n\t"
-        "titlebar_transparent: %d titlebar_color: %s title_visibility: %d hidden: %d buttons_hidden: %d"
+        "titlebar_transparent: %d titlebar_color_set: %d title_visibility: %d hidden: %d buttons_hidden: %d"
         "\n",
         window_background ? [window_background.description UTF8String] : "<nil>",
         appearance ? [appearance.name UTF8String] : "<nil>",
         cs ? (cs.localizedName ? [cs.localizedName UTF8String] : [cs.description UTF8String]) : "<nil>",
-        background_blur, has_shadow, resizable, decorations_desc, window->decorated, titlebar_transparent,
+        background_blur, has_shadow, resizable, decorations_desc, window->decorated,
-        titlebar_color ? [titlebar_color.description UTF8String] : "<nil>",
+        window->ns.last_applied_titlebar_settings.transparent, tc.was_set,
         show_text_in_titlebar, window->ns.titlebar_hidden, hide_titlebar_buttons
     );
     [nsw setColorSpace:cs];
@@ -3449,9 +3468,9 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
     } else {
         [nsw setStyleMask:window->ns.pre_full_screen_style_mask | fsmask];
     }
-    if (!window->ns.titlebar_hidden && window->decorated && titlebar_color != nil && titlebar_transparent) {
+#undef tc
-        set_title_bar_background(nsw, titlebar_color);
+    apply_titlebar_color_settings(window);
-    } else clear_title_bar_background_views(nsw);
+
     // HACK: Changing the style mask can cause the first responder to be cleared
     [nsw makeFirstResponder:window->ns.view];
 }}