Forum Linux.général Un portable, un LCD et un CRT: comment avoir un bureau étendu?

J'aimerai utiliser un écran CRT (Sony G400P) avec une résolution de 1280x1024 comme "Ecran à droite de" l'écran LCD au format 16:10 (soit 1280x800) du notebook.
Ce dernier a une carte Ati X700 Mobility (qui utilise le module ati, parce le module fxglx et xorg ne sont pas encore à la dernière version sous Ubuntu).

Avec la config ci-dessous, j'ai un écran CRT 640x480 31,3KHz/60Hz qui clone une partie de l'image LCD (il se comporte comme un bureau virtuel ou "comment avoir le mal de mer sur la terre ferme"):

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following commands:
#
# cp /etc/X11/xorg.conf /etc/X11/xorg.conf.custom
# sudo sh -c 'md5sum /etc/X11/xorg.conf >/var/lib/xfree86/xorg.conf.md5sum'
# sudo dpkg-reconfigure xserver-xorg

Section "Files"
FontPath "unix/:7100" # local font server
# if the local font server has problems, we can fall back on these
FontPath "/usr/lib/X11/fonts/misc"
FontPath "/usr/lib/X11/fonts/cyrillic"
FontPath "/usr/lib/X11/fonts/100dpi/:unscaled"
FontPath "/usr/lib/X11/fonts/75dpi/:unscaled"
FontPath "/usr/lib/X11/fonts/Type1"
FontPath "/usr/lib/X11/fonts/CID"
FontPath "/usr/lib/X11/fonts/100dpi"
FontPath "/usr/lib/X11/fonts/75dpi"
# paths to defoma fonts
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/CID"
EndSection

Section "Module"
Load "bitmap"
Load "dbe"
Load "ddc"
Load "dri"
Load "extmod"
Load "freetype"
Load "glx"
Load "int10"
Load "record"
Load "type1"
Load "vbe"
EndSection

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "keyboard"
Option "CoreKeyboard"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "ch"
Option "XkbOptions" "fr"
EndSection

Section "InputDevice"
Identifier "External Mouse"
Driver "mouse"
Option "Device" "/dev/input/mouse1"
Option "Protocol" "ImPS/2"
Option "Emulate3Buttons" "true"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
Identifier "Synaptics Touchpad"
Driver "synaptics"
#Option "Device" "/dev/psaux"
Option "Device" "/dev/input/mouse0"
Option "Protocol" "auto-dev"
Option "LeftEdge" "0"#"1900"
Option "RightEdge" "5400"
Option "TopEdge" "0" #"1900"
Option "BottomEdge" "4000"

Option "FingerLow" "25"
Option "FingerHigh" "30"

Option "MaxTapTime" "0"
Option "MaxTapMove" "220"

# Option "VertScrollDelta" "100"
Option "MinSpeed" "0.02"
Option "MaxSpeed" "0.18"
Option "AccelFactor" "0.0010"
Option "SHMConfig" "on"
Option "UpDownScrolling" "1"

Option "RTCornerButton" "0"
Option "BTCornerButton" "0"
Option "LBCornerButton" "0"
Option "RBCornerButton" "0"

Option "VertScrollDelta" "100"
Option "HorizScrollDelta" "100"

Option "CircularScrolling" "1"
Option "CircScrollTrigger" "4"
EndSection

Section "Device"
Identifier "ATI Technologies, Inc. Radeon Mobility X700 (RV410)"
Driver "ati"
Option "MonitorLayout" "LVDS, CRT"
BusID "PCI:1:0:0"
EndSection

Section "Device"
Identifier "Sortie VGA"
Driver "ati"
BusID "PCI:1:0:0"
EndSection

Section "Monitor"
Identifier "LCD du portable"
Option "DPMS"
HorizSync 30-67
VertRefresh 30-60
Modeline "1280x800@60" 83.91 1280 1312 1624 1656 800 816 824 841
EndSection

Section "Monitor"
Identifier "Ecran Sony"
VendorName "Sony"
ModelName "CPD-G400P"
HorizSync 30-107
VertRefresh 48-120
Modeline "1600x1200" 220 1600 1616 1808 2080 1200 1204 1207 1244
Modeline "1280x1024" 157.50 1280 1344 1504 1728 1024 1025 1028 1072
Modeline "1152x864" 137.65 1152 1184 1312 1536 864 866 885 902
Modeline "1024x768" 115.50 1024 1056 1248 1440 768 771 781 802
Modeline "800x600" 69.65 800 864 928 1088 600 604 610 640
Modeline "640x480" 45.80 640 672 768 864 480 488 494 530
Option "dpms"
EndSection


Section "Screen"
Identifier "Ecran Externe"
Device "Sortie VGA"
Monitor "Ecran Sony"
DefaultDepth 24
Option "DPMS"
SubSection "Display"
Depth 8
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1600x1200" "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
EndSection

Section "Screen"
Identifier "Default Screen"
Device "ATI Technologies, Inc. Radeon Mobility X700 (RV410)"
Monitor "LCD du portable"
DefaultDepth 24
SubSection "Display"
Depth 1
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x800"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x800"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "Default Screen" 0 0
Screen 1 "Ecran Externe" RightOf "Default Screen"
InputDevice "Generic Keyboard"
InputDevice "External Mouse" "SendCoreEvents"
InputDevice "Synaptics Touchpad" "CorePointer"
EndSection

Section "DRI"
Mode 0666
EndSection