Well you agree, the wall keeps its lengthwise axis. You say: you can set wall thickness for each wall individually, (and than manually recompute the correct positions to room) - waw! that's wonderful feature! I said: why do I need to recompute anything manually while using computer? Please, look ...

If there is anything clever, as the Adobe Illustrator, OOo Draw, and other program really are, any smart programmer can profit by getting good idea from them.
In your more experienced proceeding, you omitted the fact, that some houses have various wall thickness (inner, outer). While your advice ...

Well, the problem is: while creating the walls from room, the result keeps the room space, but if changing the wall thickness I cannot tell, which part of the wall have to keep its position. Example: room 300x300 [cm], default wall thickness 50 [cm]. I want to build next neighbor room and the middle ...