If you're using nvidia drivers, you can activate the external monitor from the command line.
The following script is what I do. The monitor needs to be connected first. Essentially, this script bypasses opening the nvidia control panel etc etc.
To make it work with your hardware, go through each line in a shell and look at the output, including the commented out here.

I have this script mapped to a key combination. I found this to be the best solution for me. I don't have twinview enabled by default.

Code: Select all

#!/bin/bash
nv-control-dpy --print-current-metamode | grep "id=100"
if [ $? -ne 0 ]
then
   nv-control-dpy --probe-dpys
   nv-control-dpy --build-modepool
   #nv-control-dpy --get-associated-dpys
   nv-control-dpy --set-associated-dpys 0x00010001
   nv-control-dpy --add-metamode 'CRT-0: nvidia-auto-select,DFP-0: nvidia-auto-select'
   xrandr -s 3200x1080@100

else
   xrandr -s 1280x800@50
fi


I can confirm this bug as well in aptosid (KDE 4.4.5). This is NOT NVIDIA's fault, as GNome does NOT exhibit this problem.

In GNome, I can
1) go to nvidia-settings, set up TwinView
2) have desktop background on external monitor, maximize windows, play fullscreen video, etc...

In KDE I can only do number 1. This sucks. This means no full screen video for me on my HD TV. How come GNome can do what KDE cannot?

This means no full screen video for me on my HD TV

It should work like this:

Open nvidia-settings and enable TwinView. Apply settings.
Then change the resolution of the external monitor to something else (doesn't matter what) and click "Apply". When it asks you if you want to keep the settings click "No".

Now everything should be working correctly.

I don't know why this "trick" is needed, though.

This is occurring to me as well. Any information on whether this might have fixed itself in KDE 4.5, or has anyone discovered any workarounds?

Vortex375 wrote:It should work like this:

Open nvidia-settings and enable TwinView. Apply settings.
Then change the resolution of the external monitor to something else (doesn't matter what) and click "Apply". When it asks you if you want to keep the settings click "No".

I can confirm that this "trick" works. Looks like Kwin doesn't detect the new display on activating it, but only when you change resolutions.

Now when there's a workaround known, a bug report is probably good idea..

Please file a report at bugs.kde.org.