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
Nested main loops are bad, as they introduce layers of complexity caused
by the potential re-entrancy in the case of multiple event sources, like
IPC, threads, etc. Additionally, the programming model they provide—stop
the world while spinning a new loop—does not conform to the event-driven
model employed by GTK.
It is unreliable to use the widget dom api to locate
action widgets. For example in a headerbar, they might
be deeper in the hierarchy, with boxes in between.
Therefore, make GtkDialog keep a list of action widgets,
and use that when operating on action widgets.
This was only living in gtkcontainer.c for historic
reasons. Move it closer to where it belongs, and
rename it from 'idle' to 'layout', since it is
really about the layout phase of the frame clock,
nowadays.
There are two ways GTK can add a headerbar to a dialog:
- the dialog is constructed with the :use-header-bar property
- all windows should use client-side decorations
In the first case, the headerbar is added by GtkDialog with no
dedicated style class, and in the latter by GtkWindow with the
"default-decoration" style.
As a result, dialogs with plain titlebars can end up with clearly
distinct and inconsistent styles.
To address this, allow headerbars to track whether they should use
the "default-decoration" style and enable it for dialogs.
https://gitlab.gnome.org/GNOME/gtk/merge_requests/836
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.
GDK has a lock to mark critical sections inside the backends.
Additionally, code that would re-enter into the GTK main loop was
supposed to hold the lock.
Back in the Good Old Days™ this was guaranteed to kind of work only on
the X11 backend, and would cause a neat explosion on any other GDK
backend.
During GTK+ 3.x we deprecated the API to enter and leave the critical
sections, and now we can remove all the internal uses of the lock, since
external API that uses GTK+ 4.x won't be able to hold the GDK lock.
https://bugzilla.gnome.org/show_bug.cgi?id=793124
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.
