Sometimes not all actual application windows listed in window buttons panel area.
Submitted by iza..@..il.com
Assigned to Nick Schermer
I am running ubuntu 11.04 and xfce 4.8 on 2 display machine and sometimes panel is missing all windows from specific display.
I configured 2 panels on each display with parameter to display only windows from associated display.
If you need more info I will gladly provide it.