I have an i810 system which has run KDE, GNOME, and Fluxbox with a wide variety of displays. Recently I'm borrowing a 1440x900 60Hz LCD.
In all the other systems, I can use all the display modes I have set up in /etc/X11/xorg.conf. But in XFCE, there a Screen and Graphics Preferences dialog which only presents one or two of the many, many modelines I have tested and know are usable. Right now it only offers 1280x1024 and 1280x960.
Where does Screen and Graphics Preferences get its (wrong) information about what the Xorg server is capable of? Is there a file I can edit to override Xfce's list of modelines? Is there a way to force Xfce to use 1440x900?
In the "Screen" tab of the Screen and Graphics Preferences dialog, there is a button labeled "Custom 1" with a label "Model:" just to the left of it. when I click that button, I get a new dialog titled "Choose Screen" with selections labeled "manufacturer" and "model." Of course my recently made Chinese flat screen monitor is not among the choices. So I chose Generic and LCD Panel 1440x900 and clicked the "Add" button. Thios causes a dialog labeled Choose a Driver File to appear. A driver file? For a MONITOR? This is unix. Monitors don't have drivers. What file is it really looking for? Is this mysterious Xfce Monitor Driver File documented somewhere? How do I write one?
Incidently, hundreds of people are asking about this exact problem in the Xubuntu forums, and nobody has an answer.
You are referring to something that is packaged with xubuntu but is not xfce-specific:
This is a frontend to the xrandr 1.2 extension since Xorg 7.2.
It will query xrandr only and thus completely ignore xorg.conf and try to guess modelines by some
ReadEDID magic that happens to be work in progress.
I'm using an intel chipset laptop too and the best results I got if I
0. set up LVDS, VGA according to readme, e.g.:
Section "Device" Identifier "Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller" Driver "intel" BusID "PCI:0:2:0" EndSection Section "Monitor" Identifier "LVDS" Option "DPMS" EndSection Section "Monitor" Identifier "VGA" Option "PreferredMode" "1280x1024" DisplaySize 380 305 # Of course the above two need adaptation EndSection Section "Screen" Identifier "Default Screen" Device "Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller" Monitor "LVDS" DefaultDepth 24 SubSection "Display" Modes "1280x800" Virtual 2560 1024 EndSubSection EndSection
1a. run xrandr from the command line to turn on VGA as clone of LVDS and resize
xrandr --output VGA --same-as LVDS xrandr --output LVDS --off xrandr --output VGA --auto --mode 1440x900
1b. search the net for other / better xrandr frontends (arandr / urandr)