Bug#496690: xdm: want to use Tab to switch from Login to Password field

["Phil Endecott" <phil_nnkdz_endecott@chezphil.org>]

I have also configured Tab to have the finish-field behaviour.  A 
mis-feature of this configuration, however, is that pressing tab while 
in the Password field will not swap back to the username field, but 
will instead try to logon.  So if the goal is consistency with other 
logon screens or other GUI apps, it is only partially successful.  I'm 
not aware of any way to fix this.

Phil.