GTK+ applications in Unity 8 (Mir)

Ryan Lortie and I have been tinkering away with making getting GTK+ applications to run in Unity 8 and as you can see below it works!

This shows me running the Unity 8 preview session. Simple Scan shows up as an option and can be launched and perform a scan.

This is only a first start, and there's still lots of work to be done. In particular:

• Applications need to set X-Ubuntu-Touch=true in their .desktop files to show in Unity 8.
• Application icons from the gnome theme do not show (bug).
• GTK+ applications don't go fullscreen (bug).
• No cursors changes (bug).
• We only support single window applications because we can't place/focus the subwindows yet (bug). We're currently faking menus and tooltips by drawing them onto the same surface.

If you are using Ubuntu 14.10 you can install the packages for this from a PPA:

$ sudo apt-add-repository ppa:ubuntu-desktop/gtk-mir
$ sudo apt-get update
$ sudo apt-get upgrade

The PPA contains a version of GTK+ with Mir support, fixes for libraries that assume you are running in X and a few select applications patched so they show in Unity 8.

The Mir backend currently on the wip/mir branch in the GTK+ git repository. We will keep developing it there until it is complete enough to propose into GTK+ master. We have updated jhbuild to support Mir so we can easily build and test this backend going forward.