I have set up dual screen under Ubuntu 12.04. I have a GeForce 8500 GT and have used the nVidia control panel to set up dual screen in "Separate screen mode". Here's the resulting xorg.conf

# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 295.33  (buildd@zirconium)  Fri Mar 30 13:38:49 UTC 2012


Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" RightOf "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "Files"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"

    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Maxdata/Belinea B1925S1W"
    HorizSync       31.0 - 83.0
    VertRefresh     56.0 - 75.0
    Option         "DPMS"
EndSection

Section "Monitor"

    # HorizSync source: builtin, VertRefresh source: builtin
    Identifier     "Monitor1"
    VendorName     "Unknown"
    ModelName      "CRT-1"
    HorizSync       28.0 - 55.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 8500 GT"
    BusID          "PCI:1:0:0"
    Screen          0
EndSection

Section "Device"
    Identifier     "Device1"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 8500 GT"
    BusID          "PCI:1:0:0"
    Screen          1
EndSection
Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "TwinView" "0"
    Option         "metamodes" "CRT-0: nvidia-auto-select +0+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"

# Removed Option "metamodes" "CRT-1: 1280x768 +0+0"
    Identifier     "Screen1"
    Device         "Device1"
    Monitor        "Monitor1"
    DefaultDepth    24
    Option         "TwinView" "0"
    Option         "metamodes" "CRT-1: 1360x768_60 +0+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

All well and good and I have a nice blank XWindow displayed on my TV (the 2nd monitor). I then fire up XBMC from a terminal on the PC monitor using

DISPLAY=:0.1 xbmc

XBMC fires up quite nicely on the TV however I can no longer use the main PC monitor / mouse / keyboard as XBMC on the TV screen seems to have focus. I was hoping to have XBMC running on the TV and let the kids use the MCE remote whilst I get on with my work on the PC monitor.

Does anyone have any idea how to overcome this? I'm presuming there's some xorg.conf fun and games needed but I've no idea where to start to be honest.