In Ubuntu lux reported:

For some reason, 1680x1050 resolution has never been available for me. When the generic LCD monitor (1680x1050) is chosen, and also when the actual monitor definition file is loaded ViewSonic vx2235-wm

I can select what would seem to be almost every other resolution, but 1680x1050.

I'll admit my xorg.conf has been raped by ATI Catalyst, however it seems that DisplayConfig should essentially be able to overcome this, since the display is being re-configured.

This is on a Dell e1705 w/ ATI X1400, Gutsy, fglrx.

/etc/X11/xorg.conf
--------------
# /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 "ServerLayout"
 Identifier "Default Layout"
   Screen 0 "aticonfig-Screen[0]" LeftOf "aticonfig-screen[1]"
   Screen 1 "aticonfig-Screen[1]" 0 0
 InputDevice "Generic Keyboard"
 InputDevice "Configured Mouse"
 InputDevice "stylus" "SendCoreEvents"
 InputDevice "cursor" "SendCoreEvents"
 InputDevice "eraser" "SendCoreEvents"
 InputDevice "Synaptics Touchpad"
EndSection

Section "Files"

 # path to defoma fonts
 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/100dpi"
 FontPath "/usr/share/X11/fonts/75dpi"
 FontPath "/usr/share/fonts/X11/misc"
 FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
 Load "i2c"
 Load "bitmap"
 Load "ddc"
 Load "dri"
 Load "extmod"
 Load "freetype"
 Load "glx"
 Load "int10"
 Load "type1"
 Load "vbe"
 Load "dbe"
 Load "GLcore"
EndSection

Section "ServerFlags"
 Option "AIGLX" "off"
EndSection

Section "InputDevice"
 Identifier "Generic Keyboard"
 Driver "kbd"
 Option "CoreKeyboard"
 Option "XkbRules" "xorg"
 Option "XkbModel" "pc105"
 Option "XkbLayout" "us"
 Option "XkbOptions" "altwin:super_win"
 Option "SHMConfig" "on"
EndSection

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

Section "InputDevice"
 Identifier "Synaptics Touchpad"
 Driver "synaptics"
 Option "SendCoreEvents" "true"
 Option "Device" "/dev/psaux"
 Option "Protocol" "auto-dev"
 Option "HorizScrollDelta" "0"
 Option "SHMConfig" "on"
 Option "LeftEdge" "1700"
 Option "RightEdge" "5300"
 Option "TopEdge" "1700"
 Option "BottomEdge" "4200"
 Option "FingerLow" "25"
 Option "FingerHigh" "30"
 Option "MaxTapTime" "180"
 Option "MaxTapMove" "220"
 Option "VertScrollDelta" "100"
 Option "MinSpeed" "0.09"
 Option "MaxSpeed" "0.18"
 Option "AccelFactor" "0.015"
 Option "EdgeMotionMinZ" "17"
 Option "EdgeMotionMaxZ" "21"
 Option "EdgeMotionMinSpeed" "30"
 Option "EdgeMotionMaxSpeed" "35"
 Option "LeftRightScrolling" "1"
 Option "UpDownScrolling" "1"
 Option "EmulateMidButtonTime" "75"
EndSection

Section "InputDevice"

                                                      # /dev/input/event
                                                      # for USB
 Identifier "stylus"
 Driver "wacom"
 Option "Device" "/dev/wacom" # Change to
 Option "Type" "stylus"
 Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"

                                                      # /dev/input/event
                                                      # for USB
 Identifier "eraser"
 Driver "wacom"
 Option "Device" "/dev/wacom" # Change to
 Option "Type" "eraser"
 Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"

                                                      # /dev/input/event
                                                      # for USB
 Identifier "cursor"
 Driver "wacom"
 Option "Device" "/dev/wacom" # Change to
 Option "Type" "cursor"
 Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

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

Section "Monitor"
 Identifier "aticonfig-Monitor[0]"
 Option "VendorName" "ATI Proprietary Driver"
 Option "ModelName" "Generic Autodetecting Monitor"
 Option "DPMS" "true"
 HorizSync 28-96
 VertRefresh 43-60
EndSection

Section "Monitor"
 Identifier "aticonfig-Monitor[1]"
 Option "VendorName" "ATI Proprietary Driver"
 Option "ModelName" "Generic Autodetecting Monitor"
 Option "DPMS" "true"
 HorizSync 28-96
 VertRefresh 43-60
EndSection

Section "Device"
   Identifier "aticonfig-Device[0]"
   Driver "fglrx"
   Option "VideoOverlay" "on"
   Option "OpenGLOverlay" "off"
   Option "DesktopSetup" "horizontal"
   BusID "PCI:1:0:0"
EndSection

Section "Device"
   Identifier "aticonfig-Device[1]"
   Driver "fglrx"
   Option "VideoOverlay" "on"
   Option "OpenGLOverlay" "off"
   BusID "PCI:1:0:1"
   Screen 1
EndSection

Section "Screen"
   Identifier "aticonfig-Screen[0]"
   Device "aticonfig-Device[0]"
   Monitor "aticonfig-Monitor[0]"
   DefaultDepth 24
   SubSection "Display"
      Viewport 0 0
      Depth 24
      Modes "1680x1050"
   EndSubSection
EndSection

Section "Screen"
   Identifier "aticonfig-Screen[1]"
   Device "aticonfig-Device[1]"
   Monitor "aticonfig-Monitor[1]"
   DefaultDepth 24
   SubSection "Display"
      Viewport 0 0
      Depth 24
      Modes "1680x1050"
   EndSubSection
EndSection

Section "DRI"
 Mode 0666
EndSection

Section "Extensions"
 Option "Composite" "Disable"
EndSection

Launchpad ref: https://bugs.edge.launchpad.net/ubuntu/+source/xorg-server/+bug/138820