Avoid auto-reconfigure of screens when I disconnect external monitor
I'm running Kubuntu 13.04 on a Dell Precision M4700 (using an nvidia driver and bumblebee, if that matters).
Whenever I connect or disconnect an external monitor, the screens automatically reconfigure, so that all windows are moved to the laptop screen when I disconnect the monitor, and the desktop automatically extends to the external monitor when I connect it. However, I don't want this behaviour, because sometimes I just disconnect the external monitor briefly, and then connect another monitor (or projector) and I don't want to have to move all windows back to the external monitor then.
I do get a dialog popup asking if I want to open the monitor settings to reconfigure screens, with three alternatives: yes, no, or try automatically. However, as I mentioned, Kubuntu tries automatically even when I don't press that button, so that dialog is pretty pointless at the moment.
Does anybody know why this happens, and if there's a way around it?