I am a Debian user and recently sent my main computer with dual monitors from stable to the testing branch.
This messed up my video settings, I no longer see in the Display applet under System Settings the tab for multiple monitors.
I can only configure monitors as cloned, although the box (in Size and Orientation) for unify outputs is not checked.
I have monitors LVDS (primary) and VGA-0 (secondary), I cannot set LVDS to the right of VGA-0 it reverts to Clone of...
How can I get back the multiple monitors tab?
What do I have to reload?
I already deleted my messed up xorg.conf and tried to reset monitors with arandr, with no luck.

It sounds like you possibly may have upgraded from the original KRandR support to the newer KScreen. Can you check if this is the case?
If this is the case, it is a little surprising as KScreen should be able to handle most screen configurations fairly well.

bcooksley wrote:It sounds like you possibly may have upgraded from the original KRandR support to the newer KScreen. Can you check if this is the case?
If this is the case, it is a little surprising as KScreen should be able to handle most screen configurations fairly well.

Hmm...I checked the available packages in the testing repo and see neither, no krandr and no kscreen...maybe install from kde-apps?

Victory! I got the dual monitor settings back.
How? Well, this is Debian stuff, but in short, backed up my settings in .home, exported bookmarks, address books, etc.
Then burned a netinst CD with the testing branch of Debian arch amd-64.
Reloaded everything from scratch, but this time I had all new kernel and did not have to bother to update software, everything was the latest testing.
The important thing is to do this with the minimal stuff connected, in a laptop you don't need practically anything, you leave hardware detection for later.
When all drivers are loaded, you reconnect one device at a time, configure.
I left the external monitor for last, KDE detected it and with the tool I could configure it without any problem, sweet.

Good to hear. The package name is likely something different under Debian I suspect, which explains why neither returned a result.