To build a better world sometimes means having to tear the old one down.
-- Alexander Pierce, "Captain America: The Winter Soldier"
ATK served us well for nearly 20 years, but the world has changed, and
GTK has changed with it. Now ATK is mostly a hindrance towards improving
the accessibility stack:
- it maps to a very specific implementation, AT-SPI, which is Linux and
Unix specific
- it requires implementing the same functionality in three different
layers of the stack: AT-SPI, ATK, and GTK
- only GTK uses it; every other Linux and Unix toolkit and application
talks to AT-SPI directly, including assistive technologies
Sadly, we cannot incrementally port GTK to a new accessibility stack;
since ATK insulates us entirely from the underlying implementation, we
cannot replace it piecemeal. Instead, we're going to remove everything
and then incrementally build on a clean slate:
- add an "accessible" interface, implemented by GTK objects directly,
which describe the accessible role and state changes for every UI
element
- add an "assistive technology context" to proxy a native accessibility
API, and assign it to every widget
- implement the AT context depending on the platform
For more information, see: https://gitlab.gnome.org/GNOME/gtk/-/issues/2833
We want to remove GtkBin and GtkContainer as they don't
provide much useful functionality anymore. This requires
us to move get_request_mode and compute_expand down.
Update the accessible implementation to match, remove
remnants of container implementations in GtkWindow
subclasses, and fix livecycle issues around destroy
vs dispose in GtkAssistant.
After this commit, using gtk_container_add on window
subclasses is not allowed anymore, but adding childing
with <child> in ui files still works.
See #2681
Similar to previous removals of g_cclosure_marshal_VOID__VOID we can remove
other marshallers for which are a simple G_TYPE_NONE with single parameter.
In those cases, GLib will setup both a c_marshaller and va_marshaller for
us. Before this commit, we would not get a va_marshaller because the
c_marshaller is set.
Related to GNOME/Initiatives#10
If we set c_marshaller manually, then g_signal_newv() will not setup a
va_marshaller for us. However, if we provide c_marshaller as NULL, it will
setup both the c_marshaller (to g_cclosure_marshal_VOID__VOID) and
va_marshaller (to g_cclosure_marshal_VOID__VOIDv) for us.
Change the reorder api to insert after a sibling,
so that moving to first place becomes reorder (... NULL).
And add a insert_after api that can replace the common
container_add / reorder_after (... NULL) combination.
Update all callers.
Remove all the old 2.x and 3.x version annotations.
GTK+ 4 is a new start, and from the perspective of a
GTK+ 4 developer all these APIs have been around since
the beginning.
The event is not useful at all, so we are better off
with a signal that doesn't have it, and it is only
relevant on toplevel windows, so we don't need it on
GtkWidget.
With this commit, delete events no longer go through the
::event, ::delete-event, ::event-after widget signals,
but just cause the ::close-request signal on GtkWindow to be
emitted.
