Created attachment 158613 [details]
Screenshot illustrating the situation with panels

Behaviour that has changed since upgrading from Fedora 11 to Fedora 12.
F11 behaviour was OK.

How to reproduce:

1) Connect a monitor to Laptop.
2) Monitor might be enabled by default, if not enable it with gnome-display-preferences.
Once monitor is enabled, it's by default on right side of laptop display. At that point, laptop is considered as primary display by the system. 
3) Open up gnome-display-preferences and drag the monitors around (external on left, laptop on right) and press apply. 

Actual results:
laptop appears to stay primary monitor with gnome panel while all the desktop items are moved to external monitor on left.

Expected results:
External monitor is primary monitor with desktop items and gnome panel on it.

Workaround:
- Enable external display, disable laptop display. Now external display is primary monitor with gnome panel.
- Enable laptop display from terminal using xrandr. Now both monitors are enabled and external still being the primary with gnome-panel.


System
Linux lc4eb6223761680.ibm.com 2.6.32.11-99.fc12.i686.PAE #1 SMP Mon Apr 5 16:15:03 EDT 2010 i686 i686 i386 GNU/Linux
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

Control center version:
Name       : control-center
Arch       : i686
Epoch      : 1
Version    : 2.28.1
Release    : 18.fc12

xranrd -q:
LVDS1 connected 1440x900+1280+0 (normal left inverted right x axis y axis) 303mm x 190mm
   1440x900       60.0*+   50.0  
[..snip..]
VGA1 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 377mm x 302mm
   1280x1024      60.0*+   75.0  
[..snip..]
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)