When application change pipeline state NULL->READY and then READY->NULL, glimagesink will not clear glsink->window_id. After that, when application change state NULL->READY, the new_window_id is equal to window_id, glimagesink will not set window handle. It will use the internal window but not the window create by application. https://bugzilla.gnome.org/show_bug.cgi?id=765241