Multiple Display Notebook Design (Is it really that hard?)

[oceano]

Hi, I'm hoping somebody can shed light on why laptop designers
cannot/will not provide this dual video port feature.

There are a lot of people here who want to drive two displays
with a notebook. We have to jump through a lot of hoops like
buying a VTBook to drive a second display out of the cardbus
interface or getting another graphics card to fit in the PCI slot
of a docking station. Neither of these solutions work well. We
can't undock easily and there are driver/performance issues.

The way I see the problem is this:

All the graphics card provide TWO ports, one for the laptop display
and a second port out the back or on the side. The PCI graphics
cards for desktop machines all have two ports as well.

Why can't the laptop manufacturers provide TWO external
video ports out of the laptop? If the lid is closed, the video signal
that goes to the laptop LCD should be redirected out of the
second video port. I'm not a hardware designer but this shouldn't
be that hard. Split the signal wires that goes from the graphics
chipset into two and have a switch of some kind that control
where it goes.

This logic can exist in a docking station even. Pipe the two
output signals out of the graphics chipset into the docking
station and have the docking station drive the signal out of
two DVI ports.

But no. The manufacturers must have HARDWIRED one of the
ports to the laptop's LCD. The second port's signal is not
hardwired. It can either go out of the VGA port on the laptop
or out of the VGA or DVI port on the docking station.

So only one video port is flexible like this. If they can do this
for one, they must be able to do this for the other one as well.
So why not do this? I don't think it adds that much to the cost
of the laptop.

Any PC designers or hardware engineers like to comment on this?

-Oceano