Best way I can sum it up

I have an application that has been successfully run on HP workstations under HP-UX and on a PC with LynxOS (XFree86 and Less Tiff) using mwm.
I've ported the code to the same PC that LynxOS ran on (same video card etc). I installed RedHat 9.x on the PC along with XFree86 and LessTiff. The only significant difference is that I'm stuck with the gnome as the window manager and not MWM.
The problem is with a dialog box that is refreshed as a periodic task until closed. It flashes and jumps around on the screen. I've disable the calls to XtAppAddTimeOut and the behavior continues.
I've tried running it on different hardware ( a different PC with a different video card)

If you need mwm features, uninstall lesstiff and install open motif instead
http://www.openmotif.org

It will install motif libs, programs plus mwm

will this allow me to replace the gnome desktop with either mwm or twm ? I can't isolate the problem but it would appear that gnome is interfering with the dialog box.