The programs that pop up for configuring the keyboard, mouse, networking, etc. should be set to pop up in the center with foo.set_position (gtk.WIN_POS_CENTER).
This change was made to firstboot_gui_window.py in rhpl, but since the firstboot screens inherit from that, it should "ripple" down. Get it? Heh. ;) Should be fixed in rhpl-0.20-1