On a laptop (model older) I have two screens (one built in, one external). I wish to use them both at the same time, but the settings app complains: Requested size (2944, 1080) exceeds 3D hardware limit (2048, 2048). You must either rearrange the displays so that they fit within a (2048, 2048) square or select the Ubuntu 2D session at login. The problem though, Unity 2D has been discontinued. I have forced Ubuntu to render Unity in 2D mode (with the help of echo export UNITY_LOW_GFX_MODE=1 >> .xprofile in accordance to this askubuntu post. But the error message still remains. How can one get the resolution that my computer supports? Or, how can I assure Ubuntu that it truly does use a 2D session?