Why is my layer shadow clipped to my NSView's rect?

Question

I'm creating a window containing an NSButton (both window content view & button have wantsLayer = YES), and setting the NSButton's shadowColor, shadowRadius, shadowOpacity and shadowOffset. But my shadow gets clipped to the rect of the NSView. How do I fix this?

NSRect          wdBox = NSMakeRect(0,0,100,100);
NSWindow    *   theWindow = [[[NSWindow alloc] initWithContentRect: wdBox styleMask: NSTitledWindowMask | NSClosableWindowMask | NSMiniaturizableWindowMask | NSResizableWindowMask backing: NSBackingStoreBuffered defer: NO] autorelease];
NSView* cv = [[[NSView alloc] initWithFrame: wdBox] autorelease];
cv.wantsLayer = YES;
[cv setLayerUsesCoreImageFilters: YES];
theWindow.contentView = cv;
[theWindow setCollectionBehavior: NSWindowCollectionBehaviorFullScreenPrimary];
[theWindow setTitle: @"foo"];

NSButton* mView = [[NSButton alloc] initWithFrame: NSMakeRect(10, 10, 100, 80)];
[mView setLayerUsesCoreImageFilters: YES];
[mView setWantsLayer: YES];
mView.layer.masksToBounds = NO;
[mView.layer setShadowColor: [NSColor.redColor CGColor]];
[mView.layer setShadowOffset: CGSizeMake(4, 4)];
[mView.layer setShadowRadius: 8];
[mView.layer setShadowOpacity: 1.0];
[mView setBezelStyle: NSRoundRectBezelStyle];
[mView setTitle: @"bar"];
[theWindow.contentView addSubview: mView];

Here's a picture:

I had similar code before and it used to work until 10.9, but the shadow suddenly got clipped to the view, so I rewrote it to this simple case, but it's still clipped.

Answer 1

There is a bug in Mavericks. If you create an NSButton in XIB and give it a layer and set its shadow it works fine, but if you create one programmatically it clips its shadow.

I suspect the AppKit team did some crazy hacks when they made buttons do fast layer compositing in Mavericks (they won't redraw their backgrounds unless necessary now, for instance), because they tried to make it all happen magically, which is always always a bad idea.

Note that if you make an NSTextField the shadow code works as you'd expect. It's just NSButtons (so far) that I've found have this issue.

Please file a radar.