Borderless NSWindow with rounded corners

I am creating a custom NSWindow with no title bar and am using NSBorderlessWindowMask to make it completely borderless. The problem I have with this however is that the window has sharp edges. As well as this there is no resize control.

How would I give a borderless window rounded corners?

This is not a duplicate of this question as that question was more about removing the title bar and it currently holds no answers.


  • You can make the window totally transparent and handle drawing everything yourself. The sample I have is for an OpenGL view, but it should work for a Quartz view or Cocoa view as well.

    Add the following to the initializer of your NSWindow subclass where you create the new window using the NSBorderlessWindowMask constant.

    [self setOpaque:NO];
    [self setBackgroundColor:[NSColor clearColor]]; 

    You will probably have to draw the resize control yourself. The sample I took this from is a full screen window so resizing isn't necessary.

    Good Luck.