[Wlug] FC3 + weird gui issue...

I recently upgraded this machine (was running FC2) to FC3 test3. Everything works great, but I noticed one really odd anomaly. If I open up an app, and move it to the second head (this machine has duel monitors and is running Xinerama) it disappears from the task bar. Now if I pick the app up and move it back over to the primary monitor it reappears on the task bar. I've routed through the settings, and nothing *looks* amiss. Anybody got any ideas? Later, Tim.