Question about dual monitors

[Jean Hollis Weber]

Daniel is helping me set up my laptop with an external monitor as 
an extension of the screen. Thus far all his testing has been 
with his own laptop and monitor, not mine. Today I found time to 
try the xorg.conf file on my own machine.

I have got rather lost in the threads on this topic, so if I've 
missed something that I should have set or changed in the 
xorg.conf file that I'm pasting in below, please forgive me and 
gently set me right.

The external monitor is plugged in and turned on when I boot 
Ubuntu. Xinerama is (AFAIK) installed. I did "sudo aptitude 
search xinerama" and found the same collection of files that 
Daniel listed in a previous note. So I think I have the 
prerequisites.

Below is the xorg.conf file I've tried, both with and without 
i810rotate previously started (that is, with the second monitor 
displaying as a clone, or blank). In both cases, whatever is on 
the second monitor is what I see after killing gdm and restarting 
it: if it's a clone before, it's a clone after. If it's blank 
before, it's blank after. Otherwise, all works: I get no error 
messages, and X does not crash. Should there be a log I should 
look at and post here?

Thank you for listening and for any further help you can offer
--Jean

--------------------------
# /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 command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section "Files"
	FontPath	"/usr/share/X11/fonts/misc"
	FontPath	"/usr/share/X11/fonts/cyrillic"
	FontPath	"/usr/share/X11/fonts/100dpi/:unscaled"
	FontPath	"/usr/share/X11/fonts/75dpi/:unscaled"
	FontPath	"/usr/share/X11/fonts/Type1"
	FontPath	"/usr/share/X11/fonts/CID"
	FontPath	"/usr/share/X11/fonts/100dpi"
	FontPath	"/usr/share/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	"GLcore"
	Load	"i2c"
	Load	"bitmap"
	Load	"ddc"
	Load	"dri"
	Load	"extmod"
	Load	"freetype"
	Load	"glx"
	Load	"int10"
	Load	"type1"
	Load	"vbe"
EndSection

Section "InputDevice"
	Identifier	"Generic Keyboard"
	Driver		"kbd"
	Option		"CoreKeyboard"
	Option		"XkbRules"	"xorg"
	Option		"XkbModel"	"pc104"
	Option		"XkbLayout"	"us"
EndSection

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

Section "InputDevice"
	Identifier	"Synaptics Touchpad"
	Driver		"synaptics"
	Option		"SendCoreEvents"	"true"
	Option		"Device"		"/dev/psaux"
	Option		"Protocol"		"auto-dev"
	Option		"HorizScrollDelta"	"0"
EndSection

Section "Device"
	Screen		0
	Identifier	"Intel Corporation 82852/855GM Integrated Graphics 
Device"
	Driver		"i810"
	BusID		"PCI:0:2:0"
EndSection

Section "Device"
	Screen		1
	Identifier	"Intel Corporation 82852/855GM Integrated Graphics 
Device"
	Driver		"i810"
	BusID		"PCI:0:2:0"
EndSection

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

Section "Monitor"
	Identifier	"External Monitor"
	Option		"DPMS"
	HorizSync       30-70
	VertRefresh     50-160
EndSection

Section "Screen"
	Identifier	"Default Screen"
	Device		"Intel Corporation 82852/855GM Integrated Graphics Device"
	Monitor		"Generic Monitor"
	DefaultDepth	24
	SubSection "Display"
		Depth		1
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		4
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		8
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		16
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		24
		Modes		"1400x1050"
	EndSubSection
EndSection

Section "Screen"
	Identifier	"Secondary Screen"
	Device		"Intel Corporation 82852/855GM Integrated Graphics Device"
	Monitor		"External Monitor"
	DefaultDepth	24
	SubSection "Display"
		Depth		1
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		4
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		8
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		16
		Modes		"1400x1050"
	EndSubSection
	SubSection "Display"
		Depth		24
		Modes		"1400x1050"
	EndSubSection
EndSection

Section "ServerLayout"
	Identifier	"Default Layout"
	Screen		0	"Default Screen"	0	0
	Screen		1	"Secondary Screen"	LeftOf	"Default Screen"
#	Option		"Clone" "On"
	Option		"Xinerama" "On"
	InputDevice	"Generic Keyboard"
	InputDevice	"Configured Mouse"
	InputDevice	"Synaptics Touchpad"
EndSection

Section "DRI"
	Mode	0666
EndSection