Sprinkle various g_assert() around the code where gcc cannot figure out
on its own that a variable is not NULL and too much refactoring would be
needed to make it do that.
Also fix usage of g_assert_nonnull(x) to use g_assert(x) because the
first is not marked as G_GNUC_NORETURN because of course GTester
supports not aborting on aborts.
The `rename-to` annotation is used to "shadow" a symbol with another
one, which means both symbols need to exist. It can't be used to rename
a symbol to something else.
This way, we can ensure that for local same-type drops the GValue
is set when ::enter is emitted.
This is the common case for dnd between widgets inside larger
applications, so it's worth it to speed it up.
Before, gtk_drag_icon_new_for_drag() allowed creating new drag icons.
This could cause multiple drag icons to exist for a single drag.
Now, gtk_drag_icon_get_for_drag() makes sure that only one drag icon is
created.
This is a huge reorganization of GtkDropTarget. I did not know how to
split this up, so it's unfortunately all one commit.
Highlights:
- Split GtkDropTarget into GtkDropTarget and GtkDropTargetAsync
GtkDropTarget is the simple one that only works with GTypes and offers
a synchronous interface.
GtkDropTargetAsync retains the full old functionality and allows
handling mime types.
- Drop events are handled differently
Instead of picking a single drop target and sending all DND events to
it, every event is sent to every drop target. The first one to handle
the event gets to call gdk_drop_status(), further handlers do not
interact with the GdkDrop.
Of course, for the ultimate GDK_DROP_STARTING event, only the first
one to accept the drop gets to handle it.
This allows stacking DND event controllers that aren't necessarily
interested in handling the event or that might decide later to drop
it.
- Port all widgets to either of those
Both have a somewhat changed API due to the new event handling.
For the ones who should use the sync version, lots of cleanup was
involved to operate on a sync API.
First, it should have been a GdkDrop, but even then, proper DND code
should not rely on internals.
It's only been used in an unused signal emission anyway.
