VGA monitor with PowerBook 5300cs

[davidl@porthos.bio.ub.es (David Lorenzo)]

I have just bought a SVGA monitor to use with my PowerBook 5300cs. But
when I plug the monitor to the computer, the Powerbook LCD screen remains
on, and some
programs do not support two monitors. Therefore, the VGA monitor switchs
off.

What I need is some extension or control panel (in case it exists) which can
switch off the PowerBook LCD screen wen I plug the external monitor.

Has anybody heard of something like this?

Thank you in advance,

-- 
David Lorenzo
Universitat de Barcelona
SPAIN