I use parallax mapping myself, but the buildings would ideally need to be converted into autotiles and placed in TileA. I'll try to figure out how to do that sometime. Or if someone familiar with autotiles wants to give it a shot, it would be much appreciated!
If you would rather stick to conventional mapping, there are two alternatives:
1) Use things like windows and signs as events with !$ in front of the file name
2) You can use an art program (it's easier if you have a grid and layers in, say, Photoshop or Gimp) and put the windows on a wall background. This will make the windows less versatile, but you'll be able to map as usual. The only down side to this is that you'll have to use the windows with a particular wall. My tiles are set on a 32x32 grid, so it shouldn't be too hard to figure out. If you're having issues with this, just let me know the window/wall combo and I will put them in a separate file for you