This command line tool allows DCOP KDE3 user scripting of the running window manager (any EWMH-compatible window manager, including KDE's KWin, GNOME's Metacity, Compiz and others).
It can be also used as a replacement for the wmctrl tool, which no longer seem to be maintained. It also provides more features than just directly mapping to the window manager specifications and as such it should be more easy and convenient to use.