One single tool then I would bet that Xara can do all these things but I would break the process up into getting your filled in floor + texture right as a big PNG file and then secondly. populating all the movable stuff and trees and so on with the drag and drop bitmap thing. Because the first is a bitmap editing job and PS, Gimp, Xara, PSP etc will all do that with ease and then the second use a stamp tool or a VTT. Dundjinni, my ViewingDale, MapTool, DungeonForge, FractalMapper, CC3 and so on will do that easier than with layers on any kind of bitmap editor.