An ARGB window with a frame is likely something like a transparent terminal. It looks awful (and breaks transparency) to draw a big opaque black shadow under the window, so clip out the region under the terminal from the shadow we draw. Add meta_window_get_frame_bounds() to get a cairo region for the outer bounds of the frame of a window, and modify the frame handling code to notice changes to the frame shape and discard a cached region. meta_frames_apply_shapes() is refactored so we can extract meta_frames_get_frame_bounds() from it. https://bugzilla.gnome.org/show_bug.cgi?id=635268 NOTE: Applied only partially, compositor part is still missing... upstream commit: https://gitlab.gnome.org/GNOME/metacity/commit/0f2e32d1