Testing the latest gtk easily

Flatpak supports forwarding accessibility support (at least in version 1.6.3), and thus allows to easily test the accessibility of the latest gtk without overhauling one's own system.

Preparation

Flatpak puts the whole thing in /var/lib/flatpak, you need to prepare for this and install gtk:

• Install flatpak: Debian systems have a flatpak package for instance (the following was tested on bullseye and buster)

• Add the gnome nightly remote:

  • sudo flatpak remote-add --if-not-exists gnome-nightly https://nightly.gnome.org/gnome-nightly.flatpakrepo 

• Check you see the gnome apps:

  • flatpak remote-ls gnome-nightly

• Install the base gnome platform (it will as well install a few dependencies)

  • flatpak install gnome-nightly org.gnome.Platform

• See it installed

  • flatpak list

Running

Once you have installed it: you can run:

• flatpak run --socket=x11 org.gnome.Platform

This will open a new shell. The --socket=x11 option allows X forwarding, and the accessibility bus will also be forwarded by default. In there, you can run the gtk-provided demos:

• gtk3-demo

  gtk4-demo

Current issues

• While X11 is forwarded by flatpak, the window positioning gets lost and is not known by the application, and thus the widget positions transmitted to the accessibility bus assume that the window is at the very top left corner. In the long run (wayland) applications won't know it anyway, so this will be fixed along.
  • A way to compensate is to move your window to the very top left corner, so the assumption becomes true.