When we start a drag cancel animation, we can just keep the existing
window. The reset was only necessary to convert from cursor icon to
window and we removed the cursor handling.
The Wayland dnd surface must remain in place until the drag
is over. Setting it directly as the hardcoded window of the
widget we construct carries the danger that it might get
destroyed prematurely, e.g. when the application calls
gtk_drag_set_icon_name more than once and we recreate the
widget.
Instead, create a dedicated toplevel, and reparent the widget
into it. To keep the code simple, we use the same approach
under X11 as well, and make it the responsibility of the
GDK dnd code to keep the window position updated. We already
pass the current pointer position to gdk_drag_motion, which
makes this very easy.
As a side-effect of these changes, it is now possible to use
non-toplevel widgets as drag icons.
https://bugzilla.gnome.org/show_bug.cgi?id=748763
The size of icons is a property that is relevant to who is rendering the
icon, not to the icon itself.
Example: Starting a DND operation from an entry icon should cause the
icon to resize (from the entr icon's size to the DND icon size).
Make gtk_icon_helper_ensure_surface() a private function that just
ensures the surface was loaded.
Add gtk_icon_helper_load_surface() that is called by the above function
and the dnd code to actually load the surface.
This is wrong by all accounts there, as we can do no tricks there to show
a "drag failed" animation, which is performed by the compositor itself
on wayland.
The current widget lookup code bails out on insensitive widgets, there's
however legit cases where we want DnD handled by a parent of the insensitive
widget, so just keep going upwards in that case.
We also use now the widget state flags, because get_sensitive() doesn't
propagate across hierarchies, so we could conceivably find a drop site
inside an insensitive widget.
https://bugzilla.gnome.org/show_bug.cgi?id=751793
Nowadays (and for quite some years now) we rely on GdkEventGrabBroken
events to be received. This fake button event seems a remnant of
the early Gtk 2.x days, and is currently even inconsistent with our
event delivery model, so just remove it.
https://bugzilla.gnome.org/show_bug.cgi?id=749737
If the icon happened to come from the drag site icon helper (ie. set through
gtk_drag_source_set_icon*), it would be referenced on the GtkDragInfo,
but not hooked into its context. This results on non visible drag windows,
until set_icon_helper() happened to be called on some path.
Add a gtk_drag_cancel() function that can be used on the
source side to cancel an ongoing drag operation. This can
be useful, e.g. if the data that is being dragged becomes
unavailable.
There was some X11-specific code before an early exit
in the functions that grab and ungrab keys during DND.
It seems to not cause a problem under Wayland, but moving
it out of the way seems right anyway.
