I used to clone my laptop's display to an external monitor by just typing
disper -c in a terminal. One of the recent updates broke this functionality. It now says
$ disper -c displays share no common resolution
A friend of mine has experienced exactly the same problem, so I don't think is has to do with my particular display configuration.
Does anybody know what happened and whether there's a workaround? It's specially annoying given that it used to work fine before.