I have two keyboard layout (Colemak and Qwerty). When I have logged into my Gnome session my keyboard layout is set to Colemak automatically. But for some reason I can't change the default GDM keyboard. So I either have to enter my password in Qwerty or change it every time GDM starts.
I'm using Arch Linux with Gnome 3.16.
Edit: I've tried to follow the instruction on the GDM article at the Arch Linux Wiki (https://wiki.archlinux.org/index.php/GDM#GDM_keyboard_layout). But I cannot find the Login Screen menu from gnome-control-center.
Edit 2: I've tried launch gnome-control-center as root and change the keyboard, it doesn't works.