Off-Topic??? <Fn>-<F4>, internal/external monitor switch-functionality on laptop

[Thetargos]

This most likely refers to your graphics adapter and the driver it
uses... Some graphic adapters (like ATi's Rage Mobilities) when using
the apropriate X driver (ati, in this case) will not be able to show
the content of the secondary display on the screen, however if you
switch to the vesa driver, you are able... By doing this, you lose
some functionality (like some 2D acceleration and XVideo extensions).
You change this in the the file XF86Config. In SuSE it should be
located at either /etc/XF86Config or /etc/X11/XF86Config, you need to
edit the file as root and change the driver in the Section "Device",
try the generic "vesa" driver and see if that works (it should work
just fine) Or use YaST to setup the display to be in dual mode.