GNOME Bugzilla – Bug 791039
Emit enter+motion after GDK_CROSSING_TOUCH_END leave
Last modified: 2018-05-02 19:30:06 UTC
After GDK emits a fake GDK_CROSSING_TOUCH_END leave event, it will consume the next motion event entirely and replace it with a GDK_CROSSING_TOUCH_BEGIN/DEVICE_CHANGE enter event. It would be more consistent with X11 to send both enter+motion, and certainly some clients like spice-gtk rely on this behavior, thus break on these fake touchscreen crossing events. The attached patch ensures both are sent. This patch is for gtk-3-22 only. It's moot for master since we don't propagate emulated events upwards.
Created attachment 364695 [details] [review] gdk: Always emit motion after enter After a pointer emulating GDK_TOUCH_END event triggering a fake leave notify with GDK_CROSSING_TOUCH_END mode, pointer_under_window will be unset, which will make the next motion/touch_update event to trigger an enter notify event again. Up till there, that's fine, however the motion event is just consumed in favor of the just synthesized enter notify event. This is unexpected to clients like spice-gtk that will only update coordinates from motion events, sending both enter and motion is more consistent with X11 and will make them happy.
I keep thinking that these semantics should be specified somewhere... of course, there's plenty of possible event sequences
Comment on attachment 364695 [details] [review] gdk: Always emit motion after enter True... X11 usually does an ok work at consistency, so toolkits wouldn't have to care that much, however things fall apart soon when you want to play along wrt emulation while supporting touch events at the same time :(. Luckily we now have a better story about handling pointer+touch with GtkGesture, and in master we only send one set of events (touch ones) for this case, which get far simpler than having to propagate both and letting widgets decide which to obey. And I actually did push the patch... I will double check master is good before closing.
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