Since I'm a Ph.D. student and a researcher at the same time, I often present my works through LCD projector. Now my laptop is Ubuntu 6.06 LTS Dapper Drake. I have to configure it for easily presenting. One thing I like the most of laptops and recent video drivers is dual monitor aka dual head. In particular, you are able to extend your laptop screen to external monitor via standard VGA out port. This is not a complex capability. Most laptops support this scheme out of box. In Ubuntu, we are not able to configure dual head via GUI. In fact, we can but need some modification to /etc/X11/xorg.conf.

Note that my laptop is BenQ S52-M36 with below hardware.

0000:00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
0000:00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
0000:00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
0000:00:1c.0 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 1 (rev 04)
0000:00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 04)
0000:00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 04)
0000:00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 04)
0000:00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 04)
0000:00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 04)
0000:00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d4)
0000:00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 04)
0000:00:1e.3 Modem: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Modem Controller (rev 04)
0000:00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 04)
0000:00:1f.1 IDE interface: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) IDE Controller (rev 04)
0000:00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 04)
0000:06:01.0 CardBus bridge: Texas Instruments PCIxx21/x515 Cardbus Controller
0000:06:01.2 FireWire (IEEE 1394): Texas Instruments OHCI Compliant IEEE 1394 Host Controller
0000:06:01.3 Mass storage controller: Texas Instruments PCIxx21 Integrated FlashMedia Controller
0000:06:03.0 Network controller: Intel Corporation PRO/Wireless 2200BG (rev 05)
0000:06:08.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)

First, I modified Device section and added a new one.

Section "Device"
        Identifier      "Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller0"
        Driver          "i810"
        BusID           "PCI:0:2:0"
        Option          "VBERestore" "TRUE"
        Option          "MonitorLayout" "CRT,LFP"
        Screen          0
EndSection

Section "Device"
        Identifier      "Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller1"
        Driver          "i810"
        BusID           "PCI:0:2:0"
        Option          "DevicePresence" "false"
        Screen          1
EndSection

Second, I added a new monitor. The external monitor should support 640x480, 800x600 and 1024x768 with reasonable refresh rate higher than 70 kHz.

Section "Monitor"
        Identifier      "Generic Monitor"
        Option          "DPMS"
EndSection

Section "Monitor"
        Identifier      "External Monitor"
        Option          "DPMS"
        HorizSync       37.0-96.0
        VertRefresh     50.0-75.0
        # 640x480 @ 72Hz (VESA) hsync: 37.9kHz
        ModeLine "640x480"    31.5  640  664  704  832    480  489  491  520 -hsync -vsync
        # 640x480 @ 75Hz (VESA) hsync: 37.5kHz
        ModeLine "640x480"    31.5  640  656  720  840    480  481  484  500 -hsync -vsync
        # 640x480 @ 85Hz (VESA) hsync: 43.3kHz
        ModeLine "640x480"    36.0  640  696  752  832    480  481  484  509 -hsync -vsync
        # 800x600 @ 72Hz (VESA) hsync: 48.1kHz
        ModeLine "800x600"    50.0  800  856  976 1040    600  637  643  666 +hsync +vsync
        # 800x600 @ 75Hz (VESA) hsync: 46.9kHz
        ModeLine "800x600"    49.5  800  816  896 1056    600  601  604  625 +hsync +vsync
        # 800x600 @ 85Hz (VESA) hsync: 53.7kHz
        ModeLine "800x600"    56.3  800  832  896 1048    600  601  604  631 +hsync +vsync
        # 1024x768 @ 70Hz (VESA) hsync: 56.5kHz
        ModeLine "1024x768"   75.0 1024 1048 1184 1328    768  771  777  806 -hsync -vsync
        # 1024x768 @ 75Hz (VESA) hsync: 60.0kHz
        ModeLine "1024x768"   78.8 1024 1040 1136 1312    768  769  772  800 +hsync +vsync
        # 1024x768 @ 85Hz (VESA) hsync: 68.7kHz
        ModeLine "1024x768"   94.5 1024 1072 1168 1376    768  769  772  808 +hsync +vsync
EndSection

Third, mapped device and monitor respectively.

Section "Screen"
        Identifier      "Default Screen"
        Device          "Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller0"
        Monitor         "Generic Monitor"
        DefaultDepth    24
        SubSection "Display"
                Depth           1
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           4
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           8
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           15
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           16
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1280x768"
        EndSubSection
EndSection

Section "Screen"
        Identifier      "VGA"
        Device          "Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller1"
        Monitor         "External Monitor"
        DefaultDepth    24
        SubSection "Display"
                Depth           24
                Modes           "1024x768" "800x600"
        EndSubSection
EndSection

Forth and the last, I modified ServerLayout section to place external screen on the right of my laptop.

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

Xinerama is turned off because I don't want to see large screen in Xinerama mode when I have only my laptop. If Xinerama is turned on, it means you always connect your laptop with external monitor. Otherwise, you will always have to move new windows placed outside visible screen area.

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