This is the feature that I never knew I wanted! It will be so awesome.
Terraria Community Forums
Xylia
Altermaven🌸🎀
block swap is to blocks as quick wall replacement is to wall tiles. 
Xylia
Except that back wall actually hammers out the walls and THEN replaces it (meaning paintings, torches, etc will be gone). This new block swap doesn't do that.