If a XI2 client started listening to touches due to a selection and then
creates an active async grab that does not include touch events, then it
currently won't get the touch end event which will produce inconsistent
view of the pending touches.
Note that we only need to consider touch listeners and can ignore
pointer emulation. Under XI2 if a active grab replaces a passive
implicit grab and the active grab does not include the button release
event, the client won't get it either.
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