[wellylug] Laptop screen switching

[Grant McLean]

I have an Acer Aspire 1350 laptop running Debain Sarge and
I can't find a way to switch between the LCD and external VGA.

If a monitor is plugged in at boot time, then all output goes
to the monitor.  If no monitor is plugged in at boot then all
output goes to the LCD.  

Regardless of whether a monitor was plugged in at boot time, 
the Fn-F5 key combination does not switch between displays.
Even at the BIOS level before I boot any OS, it won't switch.
I'm pretty sure the key works under Windows, but I don't use
Windows any more so that's a bit irrelevant.

I have found a BIOS setting that allows both LCD and external
VGA to work simultaneously from boot.  That's good enough for
my immediate needs but I'd like to get switching working if 
possible.  Separate displays via Xinerama would be even
better.

Any ideas?

Regards
Grant