GDM supports "Accessible Login" to allow users to log in to their
desktop session even if they cannot easily use the screen, mouse,
or keyboard in the usual way.  This feature allows the user to launch
assistive technologies at login time by means of special "gestures"
from the standard keyboard and from a keyboard, pointing device, or
switch device attached to the USB or PS/2 mouse port.   It also
allows the user to change the visual appearance of the login UI
before logging in, for instance to use a higher-contrast color
scheme for better visibility.  GDM only supports accessibility with
the GTK+ Greeter, so the "Greeter" parameter in gdm.conf must be
set to the GTK+ Greeter "gdmlogin".
