XNextEvent: Work around a bug in MachinariumHEADmachinarium-workaround

Machinarium has a bug where it sometimes handles every single MotionNotify event
it gets by drawing the cursor itself, regarless of whether its rendering is
keeping up.  This can result in the mouse cursor lagging behind the real mouse
position severely, making the game nearly unplayable.

Work around this problem in libX11 by discarding all but the last MotionNotify
whenever XNextEvent is called.  This breaks the proper ordering of events, but
works well enough for this particular game.

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/NextEvent.c b/src/NextEvent.c
index 69b979b..71ad354 100644
--- a/src/NextEvent.c
+++ b/src/NextEvent.c
@@ -53,6 +53,12 @@ XNextEvent (
 	_XDeq(dpy, NULL, qelt);
 	_XStoreEventCookie(dpy, event);
 	UnlockDisplay(dpy);
+
+	if (event->type == MotionNotify) {
+	    while (XCheckTypedWindowEvent(dpy, event->xmotion.window, MotionNotify, event))
+		;
+	}
+
 	return 0;
 }