I think a patch may have already landed that fixes this in d326ff67 [1].  This needs to be checked and closed if only the one commit was needed for the conversion.

[1]: https://git.gnome.org/browse/mousetrap/commit/?h=gnome3-wip&id=d326ff6884f683e3b4248c581c02f9b9765cb52f

Created attachment 270729 [details] [review]
Clean up after the GTK 3 transition

This cleans up some of the code that was introduced as a result of the first commit [1].

It's a squashed version of a commit set [2] that removes much of the dead code sitting around the affected areas.  It also switches the calls to `GObject.__init__` to use `super`, which will also call `__init__` on any of the superclasses instead of specifically on `GObject`.  This will still work it's way up to `GObject`, which is almost always in the chain.

[1]: https://git.gnome.org/browse/mousetrap/commit/?h=gnome3-wip&id=d326ff6884f683e3b4248c581c02f9b9765cb52f
[2]: https://github.com/kevin-brown/mousetrap/compare/cb21fd55...issue_69187

Review of attachment 270729 [details] [review]:

Committed 
https://git.gnome.org/browse/mousetrap/commit/?h=gnome3-wip&id=19af5086e2163f677ae7047525e346cc2bac9589

Committed:

https://git.gnome.org/browse/mousetrap/commit/?h=gnome3-wip&id=19af5086e2163f677ae7047525e346cc2bac9589