vtwm(1x) on Linux
The text d43e81e28a13, as Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny), Debian 4.0 (Etch) shipped it.
Virtual Tab Window Manager for the X Window System
Flags it lists
-
-d -
-f -
-m -
-p -
-s -
-v