Screen->Door[] = D_WALL does not change the tiles on the wall like D_OPEN, D_SHUTTER, D_LOCKED, D_BOSSLOCKED, etc. This is a major bug if the door was D_OPEN, because although the door is now supposed to be a wall, the tiles remain the same, meaning Link can go through the doorway still. It seems that D_WALKTHRU has the same problem.
Note: D_WALL is functional as it will keep shutters from opening, but it should place the wall tiles like the "Doors" tool. As for D_WALKTHRU, it will change a shuttter into a walk through wall, but it should also place the wall tiles.