Middle click to bring up the window menu, then click on it's title bar so it stays open. Now move it over to the right side of the screen under the dock. WindowMaker will dynamically change it and resize it, but because it expands to the right, it expands off the screen. :-) So move your mouse over it and it scrolls further onto the screen; move away and it snaps back (there's a WindowMaker option you need set to make it scroll, but it's a default so you should be right).

I only figured this out a few weeks ago, but it's quite handy. Have you spent anytime in the configuration program? There is a wealth of options for it.

Wade.