NSWindow 3 buttons are still gray after hide and unhide+activate

spend X hours on this. test *** combinations.
I have mac OS app without storyboard.
I also have menu status bar.
I click on the manu status bar to hide/unhide my app.

- (void) menuBarControllerStatusChanged: (BOOL) active {

     if([[NSApplication sharedApplication] isHidden])
     {
        NSImage *image = [UIImage imageNamed:@"newsFeedsAlertOFF"];
        self.mainStatusBar.image = image;
    
        NSAssert(self.windowController!=nil, @"window controll is nil");
        NSAssert(self.windowController.window!=nil, @"window  is nil");

        [[NSApplication sharedApplication] unhide:self];
        [self.windowController.window makeKeyAndOrderFront:self];
        [[NSApplication sharedApplication] activateIgnoringOtherApps:YES];

     }
     else
     {

        [NSApplication sharedApplication] hide:self];
        [[NSApplication sharedApplication] deactivate];

     }
}

The problem :
on unhide, the app is visible and active (focused) BUT the NSWindow 3 button are gray color.
ONLY if I active another app (safari for example) and return to my app, then the NSWindow 3 buttons are display with color.
In what situation the NSWindow is active and the 3 buttons are gray ? If there is no "normal" situation, maybe I need to report bug ?
attention 1 : I don't use storyboard. everthing is created by code (EXCEPT the MainMenu.xib)

attention 2 : this was tested on Mojave and Catalina .
attention3 : the 3 buttons are flickering for 0.1 seconds with their color and then turn gray.(with this sample code, but not in all code combinations I tested)
Thanks in adavnce.