cocoa - Borderless NSButton turns gray when clicked -

I am applying a little with three NSBITANS with an image set. These buttons have no limits or backgrounds. However, when I click on a button it turns into a gray rectangle.

How can I fix this? Thank you.

Create your button type as NSMomentaryChangeButton .

[myBtn setButtonType: NSMomentaryChangeButton];

If you use NSMomentaryPushInButton, you can get gray rectangle when clicking on the button.