Like Window.shapeCombineRegion, but the shape applies only to event handling. Mouse events which happen while the pointer position corresponds to an unset bit in the mask will be passed on the window below window.
An input shape is typically used with RGBA windows. The alpha channel of the window defines which pixels are invisible and allows for nicely antialiased borders, and the input shape controls where the window is “clickable”.
On the X11 platform, this requires version 1.1 of the shape extension.
On the Win32 platform, this functionality is not present and the function does nothing.