Xrandr

From openSUSE

The xrandr extension nowadays allows you to reconfigure display ports (LCD, external VGA, DVI ...) without restarting X. The following links contain useful information about how to use those features:

Multiple Displays Using XRandR

ThinkWiki

Debian

The caveats section on the latter is most interesting for those who wonder why certain X features just don't work they way the used to anymore.

Note that 10.3 automatically configures the external output on laptops via xrandr to 1024x768 without asking. See DISPLAYMANAGER_RANDR_MODE_VGA in /etc/sysconfig/displaymanager.