Hello, I am using dual monitor and I notice/think that Desktop Effect depends on my configuration of /etc/X11/xorg.conf , so I think I have modified something that make the desktop effect on dual monitor not possible. If I used single monitor it works really nice, just found it today. This is my xorg.conf (I only show the section that I have made changes for dual monitor). I am using Ubuntu Feisty. Thank you.

Section "Device"
Identifier "0 Intel"
Driver "i810"
BusID "PCI:0:2:0"
Option "MonitorLayout" "CRT,LFP"
Screen 0
Option "DRI" "false"
EndSection

Section "Device"
Identifier "1 Intel"
Driver "i810"
BusID "PCI:0:2:0"
Option "MonitorLayout" "CRT,LFP"
Screen 1
Option "DRI" "true"
EndSection

Section "Monitor"
Identifier "0 Generic Monitor"
Option "DPMS"
#HorizSync 28-51
#VertRefresh 43-60
EndSection

Section "Monitor"
Identifier "1 Generic Monitor"
Option "DPMS"
HorizSync 30-81
VertRefresh 56-76
Modeline "1280x1024@60" 108.0 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
EndSection

Section "Screen"
Identifier "0 Default Screen"
Device "0 Intel"
Monitor "0 Generic Monitor"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1280x800@60" "800x600" "640x480"
EndSubSection
EndSection

Section "Screen"
Identifier "1 Default Screen"
Device "1 Intel"
Monitor "1 Generic Monitor"
DefaultDepth 24

SubSection "Display"
Depth 24
Modes "1280x1024@60" "800x600" "640x480"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "0 Default Screen"
Screen 1 "1 Default Screen" RightOf "0 Default Screen"
Option "Xinerama" "On"
Option "Clone" "off"
InputDevice "Generic Keyboard"
InputDevice "Configured Mouse"
InputDevice "stylus" "SendCoreEvents"
InputDevice "cursor" "SendCoreEvents"
InputDevice "eraser" "SendCoreEvents"
InputDevice "Synaptics Touchpad"
EndSection

Section "DRI"
Mode 0666
EndSection