Reference

propwatch(1) on Linux

The text 16e4d37f9cc7, as Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny), Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.

a tool to monitor X11 properties

Flags it lists

propwatch(1) on Linux now