I'm using LXDE (on Lubuntu 15.04) on my laptop (which is a Lenovo X201). When I connect the laptop to an external monitor and tell LXDE to use only that (and blank the laptop monitor) - it obliges me. And I can also manually switch back. However, if I disconnect the VGA monitor, I would expect LXDE (or the X server maybe?) to switch the laptop monitor back on, either immediately or after a timeout, with the appropriate resolution. Unfortunately, this does not happen.
So, first, who is to blame? My laptop, LXDE (or another piece of software) or myself for not configuring something correctly?
Second, what can I do to make this work?