When a gtk theme uses larger shadows for the unfocused state than for the focused one, this can cause a crash in meta_frame_left_click_event. Since whether to call meta_frame_left_click_event is decided based on the decoration size before focusing and the control that was clicked on after focusing, this can result in an event handled in meta_frame_left_click_event being on the client area.
Fixes #1668 (closed)
Part-of: !1748 (merged)
(cherry picked from commit c2968c89)