My setup isn't the exact same as his but I've never had any problems plugging in a projector on my XMonad laptop. In the XMonad schema windows are always assoc

My setup isn't the exact same as his but I've never had any problems plugging in a projector on my XMonad laptop. In the XMonad schema windows are always associated with one of the 9 workspaces and each screen displays one workspace with the windows all scaled to fit nicely in the display. When you unplug a screen the windows on the associated workspace stay on that workspace and don't go anywhere else.