We can end up with _gtk_widget_remove_controller getting called
while we are iterating over the list in _gtk_widget_run_controllers.
To avoid trouble, only mark the event controller as dead by
setting data->controller to NULL, and defer the actual freeing
and list manipulation to the loop in _gtk_widget_run_controllers.
Update other places that operate on controllers to handle
data->controller being NULL.
Make it really sure that the event is only emitted after every gesture
that consumed the button press is done with the sequence.
The event must only be emulated if a gesture in the capture phase happened
to consume the event, be cancelled, and
Sequences may be cancelled within the ::sequence-state-changed handler, which
would change the points hashtable as it's being iterated in this function. So
iterate over a list of sequences and let the hashtable change freely.
The propagation phase property/methods in GtkEventController are gone,
This is now set directly on the GtkWidget add/remove controller API,
which has been made private.
The only public bit now are the new functions gtk_gesture_attach() and
gtk_gesture_detach() that will use the private API underneath.
All callers have been updated.
Within a widget, if a gesture accepts a sequence, it would previously
cancel every other gesture that not in the same group. Change this to
only cancelling gestures that previously claimed the gesture, and let
gestures with state=NONE for that sequence remain like that.
This enables late recognition of gestures, even on the presence of
another gesture group that was more eager at claiming the gesture.
One usecase is user-defined panning gestures on scrolledwindows,
if ::capture-button-press is TRUE (eg. the default), the gesture is
claimed early in order to consume the button press, but that would
tipically make every other gesture group deny the sequence. With
this change, the pan gesture can keep state=NONE, and later claim
the sequence for itself if the panning gesture is recognized.
Also, do not propagate state=DENIED to every gesture in the widget,
that was unintended.
If no match is found with the gesture widget when poking the event
window parents, bail out safely instead of falling in an infinite
loop. This was seen on Mutter.
The utility of those signals is somewhat dubious now that there is
gtk_gesture_group(), so make that the only way to coordinate gestures.
The cooperation model offered by gtk_gesture_group() is flexible
enough,
