I just got new LCD at work - Acer AL1916W. I thought it will be much easier to setup than it actually was.
First attempt was only to add "1440x900" to modes in X.org configuration. It failed as well when I added modeline for this mode. After some Googling I found that for my stupid onboard card - i945 - I need to do some voodoo with it's BIOS to make it work.
Fortunately there is tool 915resolution which does this black magic, so it was not that complicated at the end:
# aptitude install 915resolution
It complains that it can not detect display, so I had to modify
/etc/default/915resolution
manually:
MODE=5c
XRESO=1440
YRESO=900
After starting 915resolution init script, you should be now able to start X.org server with following configuration (kept only relevant parts):
Section "Monitor"
Identifier "Acer AL1916W"
Option "DPMS"
HorizSync 30-82
VertRefresh 56-76
DisplaySize 410 260
Modeline "1440x900" 136.0 1440 1520 1672 1904 900 903 909 934 +hsync +vsync
EndSection
Section "Screen"
Identifier "Default Screen"
Device "Intel i945"
Monitor "Acer AL1916W"
DefaultDepth 24
SubSection "Display"
Depth 24
Virtual 1440 900
Modes "1440x900" "1400x1050" "1280x1024" "1280x960" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
EndSection
And finally I can use widescreen display!