Because there's only one status label on a gdm screen, the timed login's
replacement of it after only five seconds poses a problem for users slow to
read or comprehend instructions (or who need to think awhile to remember a
password, or what a username is.)  Also, because the label often causes the
gdm window to resize, it incurs a nasty visual disruption (imagine here
that you're a poor typist looking at the keyboard, trying to remember a
password, and the monitor image in your peripheral vision jumps) as all the
widgets flicker, resize or move.

Suggested fix: If a timed login is enabled, it should relate what's going
to happen in an always-visible label of its own that never obscures any
instructions on the screen; ideally it should be visually separate from
instructions and entry widgets, since a timer puts both a distraction and
time-pressure stress on the user.  Updating the label should on no account
cause any disturbance to anything else -- the window should be big enough
to display the maximum timer value, and should not shrink when the timer
label does.