gdk-window-shape-combine-region (window shape-region offset-x offset-y)

window -- a gdk-window object
shape-region -- region of type cairo-region-t of window to be non-transparent
offset-x -- a :int with the x position of shape-region in window coordinates
offset-y -- a :int with the y position of shape-region in window coordinates

Makes pixels in the window outside shape-region be transparent, so that the window may be nonrectangular.

If shape-region is nil, the shape will be unset, so the whole window will be opaque again. offset-x and offset-y are ignored if shape-region is nil.

On the X11 platform, this uses an X server extension which is widely available on most common platforms, but not available on very old X servers, and occasionally the implementation will be buggy. On servers without the shape extension, this function will do nothing.

This function works on both toplevel and child windows.