Tk::LockDisplay is a Perl/Tk widget that disables an X display until a
proper authentication string is entered (typically the user's
password). The authentication subroutine is specified during widget
creation.  People often lock their display for short periods of time
when, for instance, they need to use the restroom.  It's needed around
here because folks use xlock which doesn't do AFS authentication, so
they're "inconvenienced".

While the display is locked, a simple "screen saver" is displayed in
case someone needs to waste time.  Tk::LockDisplay "wakes up" with a
key press or mouse motion, and goes away when authentication is
completed.

After some number of (user configurable) seconds of inactivity, 10 by
default, the password entry widget and logo are hidden so all that
remains is the colorful screen saver display.  The "velocity" of the
moving screen saver pattern is also user configurable.

Tk::LockDisplay ships with a few screensaver plugins, and has a hook
to register your own Perl/Tk plugin or subroutine.  The special plugin
'none' disables the screensaver animation.

LockDisplay is currently crippled on Win32 systems - it pretends the
login user name is $^O and the password is $^O (the operating system
name).  Eventually I'll make it work correctly on Windows NT.

Oh, on Windows 95/98 the "lines" plugin has a memory leak, which I
*think* is due to Tk not freeing memory when canvas lines items are
deleted.  I don't see this problem on NT or any flavor of Unix.

Installation:

	perl Makefile.PL
	make
	make test
	make install

Stephen.O.Lidie@Lehigh.EDU, 98/10/20