Why do I think so - because when replacing the Intel driver by a Generic Videoadapter Driver, this behaviour stops (although the integrated monitor doesn't switch off at all when the lid is closed, which isn't good too!). I haven't found a way to stop this disconnect/reconnect event on lid open/close, as it seems to be (sadly) managed by the Intel Graphics driver itself. It seems like the system receives a 'monitor connected' event, and it automatically reenables it. When the lid is opened, it reenables back itself and reconnects back the monitor. The desktop then jumps totally from a dual monitor setup to a single one, and only NVIDIA manages the only monitor 'left'. Now the trick is, that the HDMI port seems to be shorcircuited to the NVIDIA card instead of passing through the Intel one, so when I close the monitor lid, the Intel card thinks that the last monitor attached to it have disconnected (which is weird as it should just disable it, and not disconnect!) and just disables itself nearly totally. It have an HDMI port where I plugged an external monitor. I have a Dell G5 5587 with an NVIDIA and Intel video cards.
