Wmbutton is a 64x64 pixel application that displays nine buttons.
Each of these buttons can be configured via a configuration file
to run just about any application you’d like to. Basically, if you
can type it in a shell command, wmbutton can run it.
The graphics of in each button may, of course, be changed as well.

3 Button action for WindowMaker and 2 button action for Openbox