Since GDK client side windows (GDK 2.18), GDK_POINTER_MOTION_HINT_MASK is not implemented with X11 PointerMotionHintMask, but gdk_event_request_motions still does a gdk_device_get_state which queries the server for state, which is a round trip. This code was added in bug 459780, but is not used on Mozilla builds because of old GTK versions there. It would make sense to disable this for desktop builds against newer GTK also, so that distributions get the same mouse behaviour.
Created attachment 620148 [details] [diff] [review] disable motion hints to avoid gdk_event_request_motions unless on Maemo This leaves the motion hints on Maemo, as X11 MotionNotify compression doesn't yet properly handle extension events (bug 459780). Does anyone still build the GTK port for Maemo?