510411 - Multiple XGrabServer on LeaveNotify events

Status: RESOLVED FIXED

(Core :: Widget: Gtk, defect, P5)

Description

[Karl Tomlinson (:karlt)]

Each time gdk_display_get_window_at_pointer() is called it grabs the X server and performs multiple XQueryPointer round-trips before ungrabbing.

leave_notify_event_cb() in nsWindow.cpp causes
gdk_display_get_window_at_pointer to be called twice.

http://hg.mozilla.org/mozilla-central/file/43fdf17e10a3/widget/src/gtk2/nsWindow.cpp#l5448
http://hg.mozilla.org/mozilla-central/file/43fdf17e10a3/widget/src/gtk2/nsWindow.cpp#l2522

leave_notify_event_cb is called for each GdkWindow in the hierarchy that is crossed, so moving the mouse from browser content out of the app causes leave_notify_event_cb to be called at least 4 times, grabbing the server at least 8 times.

Comment 1

[Christopher Blizzard (:blizzard)]

Note that there are a few calls in gtk that do ServerGrabs.  (I'm told Tooltips are another item that do this - maybe also via gdk_display_get_window_at_pointer()?)  Might be worth looking and figuring out if we're running into those as well.

Comment 2

[Karl Tomlinson (:karlt)]

I expect it would be possible to detect leave events from pointer grabs by
comparing GdkEventCrossing::mode with GDK_CROSSING_GTK_GRAB.

I wonder whether is_top_level_mouse_exit() is still required.

Comment 3

[Firefox Bug Husbandry Bot]

https://bugzilla.mozilla.org/show_bug.cgi?id=1552613