"Exit" from mwm

[W. W. Looi]

I'm new to AIX environment. I wonder if there is a way to "elegantly"
exit from mwm and return to either login or console screen without
resorting to CTRL-ALT-Backspace? I was told that "xstop" will do the
job, but I don't seem to be able to locate it. Worst yet, it's not
documented anywhere in the manual. *sigh*

Also, is there any Sun-like "lockscreen" on AIX? It'd be nice if I can
freeze my screen to avoid unathorative tampering.

Any info will be appreciated. Thanks in advance.