In another post I mentioned I was working on a old prison. On one of the walls I need to put a large window at one end of the building, with huge stone mullions holding it up. I have drawn it at the moment with a brick facade, and was going to change it later with a wall of stone starting at a different level. (if this makes sense)
When I came to put the second wall in, made of stone, it doesn't allow for the opening where the window/door is in the second wall element.
Hope this makes sense.
PJ