On an 11.1 AMD64 system with nvidia 6150 (binary driver) and 15" CRT using and X using 1024x768 resolution, it works as expected. I added "Virtual 1400 900" to the default screen subsections in xorg.conf like I always do, and the virtual display works and scrolls at the boundaries, but even though I can scroll around the entire 1400x900 desktop area it seems that KDE doesn't recognize the full desktop dimensions and thinks it only has 1024x768.

The panel is drawn as if the desktop was only 1024x768, and windows maximize as if the desktop was only 1024x786. If I scroll the virtual desktop fully to the upper left, it's just like having a 1024x768 KDE desktop. I can't drag anything past that boundary, it acts like it's dragged off the screen although the background image (wallpaper) is there and the display scrolls.

This is the first time I've used KDE4 and don't see anywhere to set KDE to use the entire virtual desktop space. KDE3 just always used the entire space by default. The xrandrtray app changes between all the resolutions fine as well, but the area that KDE uses for the desktop is always pinned to 1024x768 regardless of the virtual resolution.

What do I need to do to get KDE to use the entire virtual desktop resolution provided by the X server? Is there somewhere I need to set the KDE desktop size to match the resolution of the X virtual display? Any ideas?