We should make the display settings instant apply. It is really unnatural to need to use explicit apply since no other GNOME settings use this.

Here at GNOME Asia I've seen a few people totally confused by this. One case where it was confusing that nothing happened after changing settings and another case where the user thought that the apply button was the close button and kept hitting it over and over. It seems obvious in retrospect that putting an apply button where people expect to see a close button isn't super.