Screen Resolution

[ICMan <icman eol ca>]

Can anyone tell me where I can get good documentation on the "Screen Resolution" applet?  I looked at the Wiki on gnome.org, and I have searched on Google, to no avail.  I am trying to understand how the applet interacts with xorg.conf and the X-Server.  I have several Debian images at work and at home, and some will recognize Modes higher than 1024x768, and others wont.  For example, I have a Debian image on two of my systems at home.  I changed monitors on one of them, and after a reboot or two, the applet began to recognize the 1680x1050 mode that I put in xorg.conf (didn't need a modeline, either - the Vesa driver picks this up as a supported resolution).

However, two of my other images won't support a 1280x1024 mode, even though the monitor supports this mode.  For example, the laptop I am using is connected to a Samsung SynchMaster 940B.  When it had Windows on it, 1280x1024 was supported, so I know that the video card supports this mode.  However, the Debian installation wont support this mode for some reason.  Also, I can't seem to make changes to the refresh rate.

Any help would be apprectiated.

ICMan