Comment 112 for bug 195929

Sorry that I did not think about this earlier. But can moz_gtk_init be called multiple times (eg. on a theme change)? If yes, then we should check for the style property before registering, or a warning will be printed by GTK+.
(All that would be needed is a call to gtk_widget_class_find_style_property.)

There is one small thing, that I want to say, but feel free to ignore me if you think differently ;-) (ie. you get r+ anyways)
You are setting the hint on all widgets. I do see some advantages, but I also see a disadvantage. And that is that it may be abused by engine writers to special case gecko, instead of using it only in the way that it is intended.

So r+ from me, but please check the moz_gtk_init thing before landing.