[gdm-list] Accidental password-in-username-field detection and obfuscation?

[David Finch <david mytsoftware com>]

On a certain popular operating system, the username of the last user to 
log in is the default, and and the cursor starts in the password field. 
So I just type in my password and hit enter. This often causes mixups 
when I login to my Linux desktops. I'll sometimes accidentally start 
typing my long, cryptic password in the username field, where anyone 
could see it.

It might be helpful to obscure the username if the user types 
password-like username. It could be triggered by a non-letter followed 
by a letter in their username, or a lowercase letter followed by an 
uppercase letter in a username that does not begin with uppercase. They 
could have a username that looks like a password if they really wanted, 
but GDM would "***" it out like it does the password field, by default.