This [url = http://forums.virtualbox.org/viewtopic. … 751]thread on the VirtualBox forums[/url] looks (to me) like a XFCE bug - any clues on how I could
a) troubleshoot the problem
b) work around it
The problem is that under gnome the virtualbox windows correctly position themselves in Z order whereas with XFCE the virtualbox windows are (almost*) always on top. This has been a problem for me when running various recent versions on VirtualBox (and looking at the thread above longer for others) on a variety of Xubuntu versions and thus a variety of XFCE. I am currently running Xubuntu 9.10 (i.e. xfce 4.6.1) and VirtualBox 3.1.2
* the almost is because if I start up a new XFCE window then it remains on top until I switch to a virtualbox window - at which point it goes into the background and remains there no matter what I do - even checking "alway on top" for it.
File a bug report under xfwm4