Why can't horizontal span be implemented on Vista?

Question

Until Windows Vista, ATI and nVidia supported a feature called horizontal span, which combined two monitors into a single larger screen.

This feature allows the taskbar to span across both monitors, allows games to be played in fullscreen across both monitors, and allow Remote Desktop Connection to span both monitors without the /span feature (I have four monitors, so my total screen width is more than RDP's limit of 4096 pixels, making /span very annoying. Also, the ActiveX control doesn't support it)

The Vista drivers from these companies do not support this feature, and it appears that they never will.

What changes were introduced by the WDDM that made this feature impossible?

Answer 1

Horizontal span CAN be implemented in Vista.

But not with the nVidia cards for now.

Microsoft has changed the WDDM architecture in Vista and nVidia (and other companies) should change their previous drivers to met it's requirements and can have the horizontal span.

But unfortunately nVidia didn't.

I am using Matrox Graphics cards and i HAVE the horizontal span and other features in Vista, enjoying WoW in Vista!

So this is a nVidia problem, not the MS one ;)

You and other nVidia users should ask nVidia to stop being lazy and fix theier Drivers!