xtrlock is a very minimal X display lock program, which uses
nothing except the Xlib library. It doesn't obscure the screen,
it is completely idle while the display is locked and you don't
type at it, and it doesn't do funny things to the X access control
lists.

I needed this package for a monitoring workstation at my work
and patched the Debian xtrlock for it. I haven't tested this
on Linux or other systems, just made it working on NetBSD i386
more testing is needed.

Is there a workaround for the setuid bit to lock the screen?