After taking a week or so off to focus on other projects (including finally having a few rain free hours of spare time to wash the car yesterday), I'm back to working out the last failing test case, which seems to be HildonColorChooser. Running the example works ok, but interacting with the Hue bar causes it to segfault 90%+ of the time.

I've been playing with some ideas to rewrite it/replace it but the classes uses in Gtk3 (GtkColorEditor, GtkColorScale) are private so I would have to reimplement them as well. Add the fact that gtk_color_scale_draw_trough is called by GtkRange as a special case so the implementation would have to be different anyway.