My environment is OS X Yosemite 10.10.2. Xcode are 6.1.1 and 6.2 beta4. I wrote an calendar app for OS X. I used a cocoa bindings framework that I wrote. And I got a problem. There should be only one focus day button in the collection view. But something wrong. The app has multiple focuses.
I found a statement cause this problem. [[[self view] window] setStyleMask:([[self view] window].styleMask | NSFullSizeContentViewWindowMask)]; When app sets the NSFullSizeContentViewWindowMask, only the clicked button of collection view will call drawRect because of performance. This caused my problem. - (void)drawRect:(NSRect)dirtyRect
The related post in Apple developer forum:https://devforums.apple.com/message/1097305#1097305