Draw tab color in white if the window appearance is dark. This happens to work...

Draw tab color in white if the window appearance is dark. This happens to work for the main menu (it has a window!) as well as the context menu on a tab. Issue 6286.

sources/ColorsMenuItemView.m

@@ -162,8 +162,7 @@ enum {
     while (rootMenu.supermenu) {
         rootMenu = rootMenu.supermenu;
     }
-    if (rootMenu == [NSApp mainMenu] &&
-        [[[NSUserDefaults standardUserDefaults] stringForKey:@"AppleInterfaceStyle"] isEqualToString:@"Dark"]) {
+    if ([self darkTheme]) {
         attributes[NSForegroundColorAttributeName] = [NSColor whiteColor];
     }
@@ -172,6 +171,10 @@ enum {
     [NSBezierPath setDefaultLineWidth:savedWidth];
 }
+- (BOOL)darkTheme {
+    return [self.window.appearance.name isEqual:NSAppearanceNameVibrantDark];
+}
+
 - (void)mouseUp:(NSEvent*) event {
     NSPoint mousePoint = [self convertPoint:[[self window] mouseLocationOutsideOfEventStream] fromView:nil];
     NSMenuItem* mitem = [self enclosingMenuItem];