Problems with dual monitor setup in Xfec 4.8 pre1

[Christoph Wickert]

Hi,

I'm having serious problems with Xfce 4.8 pre1 when using two screens.
The small screen is the display of my laptop, which is cloned to my new
24" display.

$ xrandr 
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
LVDS1 connected 1280x800+0+0 (normal left inverted right x axis y axis)
261mm x 163mm
   1280x800       60.0*+   50.1  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected 1920x1080+0+0 (normal left inverted right x axis y axis)
531mm x 298mm
   1920x1080      59.9*+
   1600x1200      60.0  
   1680x1050      60.0  
   1280x1024      60.0  
   1440x900       59.9  
   1280x960       60.0  
   1280x800       59.8  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        60.0  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)

Problems:

I have two wallpapers on my large screen, one is the full 1920x1080 and
the other one the 1280x800 of the laptop: Screenshot
http://cwickert.fedorapeople.org/screenshots/xfce/xfdesktop-two-screens.png

When pressing ALT+TAB I get two taskswitcher dialogs on each screen.
Screenshot: 
http://cwickert.fedorapeople.org/screenshots/xfce/xfwm4-two-taskswitchers.png

Are these different problems or is to root something deeper in the X
server?

Regards,
Christoph