ok...
Im using a custom version of the popular openmotif window manager. Its kind of IRIX looking and its a smooth transition from the SGI look.
Anyway, we faced the problem by using Alt+Shift+RMB and then release the Shift button. It works but is sometimes a little bit frustrating. You can also go into your .mwmrc (if you're using a motif wm) and remap your "move" button binding.
Check the forums at: www.openmotif.org
Good Luck!
Joda