NSButton white background when clicked

Question

When creating Cocoa bevel button with custom image and alternate image I'm having a strange behavior. In the pressed state the button background becomes white. I'm adding the button as subview of a transparent window (HUD window).

I'm trying every technique that I know:

NSButton *closeButton = [[NSButton alloc] initWithFrame:NSMakeRect(0.0, 0.0, 30.0, 30.0)];
        [closeButton setFrameOrigin:NSMakePoint(0.0, 0.0)];
        [closeButton setImagePosition:NSImageOnly];
        [closeButton setAction:@selector(closeWindowAction:)];
        [closeButton setBordered:NO];
        [closeButton setTransparent:NO];

        [closeButton setImage:[NSImage imageNamed:@"icon-tclose-off"]];
        [closeButton setAlternateImage:[NSImage imageNamed:@"icon-tclose-on"]];
        [closeButton setBezelStyle:NSShadowlessSquareBezelStyle];
        [closeButton setButtonType:NSMomentaryLightButton];

        //[[closeButton cell] setBackgroundColor:[NSColor clearColor]];
        [[closeButton cell] setHighlightsBy:NSChangeBackgroundCellMask|NSCellLightsByContents];
        //[[closeButton cell] setHighlightsBy:NSContentsCellMask];
        //[[closeButton cell] setShowsStateBy:0|NSContentsCellMask];

I also tried

[closeButton setButtonType:NSMomentaryChangeButton];

[[closeButton cell] setHighlightsBy:NSContentsCellMask];

with no results.

You can see the wrong behavior in the attached screenshots:

Bevel button overlaying a HUD window:

Wrong bevel button background:

Answer 1

Depending on your situation, this may also work:

Change the style of the button to Bevel or Square, the mode should be set to "Momentary Change" and Border, Transparent, Mixed and Selected should be OFF. This is how I fixed the white background problem on my buttons.

Answer 2

I have made it work by setting cell.highlightsBy to ContentsCellMask:

let btn = NSButton(frame: myFrame)

btn.image = myButtonImage
btn.image?.size = myFrame.size
btn.imagePosition = .ImageOnly

btn.bordered = false      
(btn.cell as? NSButtonCell)?.highlightsBy = .ContentsCellMask

view.addSubview(btn)

This way the button is darkened when pressed, but no ugly square appears. Tested only in El Capitan).