Hmm, my only complaint is that wall placement is somewhat awkward - mind you, I am comparing it to a tile based mapping program that did not have the constraints of being tied to a particular wall structure. is the program in question - and to be fair it never left Alpha (dammit!).
However, I think that a stretch and place method of drawing walls would be much easier, and less awkward, to use. I also suspect that it would be a bear to implement, but it does seem like a feature that I should request.
Actually, taking a look at DC2 might not be a bad idea in any event, while never finished DC2 and its ancestor DC1 remain part of my mapping arsenal 10 years agone. I have used them together for a long time, creating a map in DC2 then adding the doors in DC1.
Another consideration is the method used for showing doors - a better method for TLXP might be a simple pair of graphics akin to a square for doors and = for open doorways.
The Auld Grump