Currently doors can be placed (only) against walls, but once placed they cannot be moved.
For building underground structures, it would be useful to be able to freely place such objects, and to be able to move them.
For instance consider the current workflow for placing a double-door as tunnel-door:
Dig out the place where the door should go.
Make sure not to dig farther yet. If the door should sit centrally between 4x4x4 blocks of the mining tool, this requires digging out a 3x4x4 volume with the N-key tool (fiddly, needs to be done layer by layer).
Place the door.
Being able to freely place doors on the ground would allow just digging out the whole structure, and then playing the door into the tunnels. Windows would be nice too, albeit only for technically pointless decoration.
I played Dwarf Fortress for a long time, and I can only assure you jomaxro, I definitely use doors as entrance to a mine, and more importantly I dig entire houses out of mountains!
But as klaus said digging entrances for doors is very cumbersome. When youâre making an entrance to a mountain, you dig with âmâ tool and then you need to further expand that entrance with ânâ tool, which is not easy to use at all. When you expand entrance (it has to have completely different dimensions than anything else something like 816/7) it doesnât fit with anything.
By making doors and windows being able to stick to premade natural walls, that are thinned to 1 block thickness, much of this would be solved and without an issue. Since currently you cannot even make rooms with doors.
Last time I checked you couldnât place doors and windows in walls made with the slab tool. Of course it would be good to be able to do that the normal way, but this would solve that problem to.
Related: There seems to be a problem placing windows inside tunnels (meant as decoration). Apparently the hearthlings canât place a window that touches the ceiling.