It has been replaced by GdkRGBA. Time to make it official. http://bugzilla.gnome.org/show_bug.cgi?id=636695
Mark user-visible strings for translation in the new property editor.
Move away from cell editing, and use a popover instead. This makes it easier to e.g. use a color chooser - there's just not enough room in a cell for many things. Much of this code is adapted from tests/prop-editor.c.
