Traditionally (and on most backends) there's a single master pointer driven
by all pointing devices. The notable exception is Wayland though, where
master pointing devices are created per capability in the case of
pointer/touch, and one for each drawing tablet.
This function call makes it easy to access all these.
https://bugzilla.gnome.org/show_bug.cgi?id=790920
This patch makes that work using 1 of 2 options:
1. Add all missing enums to the switch statement
or
2. Cast the switch argument to a uint to avoid having to do that (mostly
for GdkEventType).
I even found a bug while doing that: clearing a GtkImage with a surface
did not notify thae surface property.
The reason for enabling this flag even though it is tedious at times is
that it is very useful when adding values to an enum, because it makes
GTK immediately warn about all the switch statements where this enum is
relevant.
And I expect changes to enums to be frequent during the GTK4 development
cycle.
gdk_seat_default_grab() grabs POINTER_EVENTS if the capability is
GDK_SEAT_CAPABILITY_ALL_POINTING. But that enumerator is a union that
includes GDK_SEAT_CAPABILITY_TOUCH, but we never grabbed TOUCH_EVENTS,
an unused macro that was presumably created with this purpose in mind.
So, check which of the ALL_POINTING capabilities we have, and set the
right mask of POINTER_EVENTS and/or TOUCH_EVENTS as required.
As part of this, explicitly let TABLET_STYLUS take over pointer events,
as this is the intended behaviour and was the effective result before.
This should fix touch events being lost in migrating from Device.grab()
to Seat.grab(GDK_SEAT_CAPABILITY_ALL_POINTING), as found by Inkscape.
https://bugzilla.gnome.org/show_bug.cgi?id=781757
