First off let me say I love Roll20 and use it all the time for my Play By Post games. One of the issues I commonly encounter is the light being cut off by the doors being open. However, if light is flooding into a room through a doorway then the other parts of the room should be lit with dim light out to a certain extent as well. In the below image the section outlined in red should techincally be dim lit not completely black because the strength of light coming through the door should still broadcast dim light out from it. I know this would probably be a technical mess to work with but it would definitely bring the dynamic lighting up to the next level in my opinon!