Possible approaches to cross-platrm shaped window?

I’m just thinking of a round cornered window. I was thinking if I could find a way to poll the screen for what’s under my opengl glut created window. Grab the corners of that data, manipulate them a bit to try and fake transparency a bit and overlay that as my last step in all draws.

I doubt this would be a very efficient way of doing this.

Then there is using GTK+ as an opengl container, but I think shaped windows are only available on X systems and not sure if the mask would work over an opengl context (is that the right term?).

As a last resort I’m sure each target system has it’s own ways of shaping windows, and using system calls to the appropriate subsystem, be it carbon/quartz, gdi, gdk+. I suppose there is always Qt, but I’d prefer a looser license for what I’m doing.

I was just hoping there might be an easier way?

Anyone have any pointers or idea’s.

Qt 4.5 is LGPL