You may have noticed at Main Menu>Universal Access>xvkbd that Klaus
has provided Tom Sato's virtual keyboard, xvkbd.

I frankly haven't really found an everyday use for it myself.
I propose that it may represent a hidden challenge that we might all
engage in, somewhat akin to Liars' poker.

The challenge is, after calling up xvkbd from the Knoppix menu,
how many ways in a standard Knoppix 6.7.1 installation can you close
the virtual keyboard gui, not counting rebooting or restarting X?
I can think of two.

If you can't think of even one, then perhaps you'd be interested
in modifying, as root, line 252 of /etc/X11/Xsession.d/45knoppix
to read 'xvkbd.nonexitable: false' rather than 'xvkbd.nonexitable: true'.
That should give you two ways you didn't have before.