Here's a tip for you when your redoing your tub surround

If you desire to retile your tub surround here are a couple of tips that will make it easier for you. In order to replace your tile without a bunch of dry wall refinishing you need to replace the existing wall board. As you probably know the joint between the new substrate and the existing needs to be taped with mesh tape and skimmed over with thinset. If this is done outside the tile you will then need to do a bunch of texturing work and painting to bring everything to a nice finish. Here's a way to do it without all those extra dry wall steps.
When you begin with the demolition start by removing the last row of tile on the out side perimeter, usually trim pieces (bull nose). Do this with care so as not to break the dry wall or wonderboard. Take a drywall knife and cut next to the edge of the tile to cut through the caulking and paint. Now take a flat bar and a hammer and carefully break the tile off of the wall. Do this around the entire perimeter. Once this is finished, now take a saw of some kind and cut right next to the tile that's still on the wall all the way through the wall board. Be careful to not cut through wires and/or plumbing while doing this.
You can now tear off the rest of the tile and wall board until it's all gone and your now down to bare studs. Now cut your new cement board to fit the empty spaces, starting first with the back wall. On the vertical joints where the new cement board will join with the existing wall board you will first have to screw in some wood backing so that you are able to screw both sides of the joint tight to the wood backing. I use cedar fence pickets for this application. They are the right width, soft enough to cut easily and easy for the screws to grab as well. Cut the fence picket to the required length and start by screwing it to the existing wall board on the back side of the wallboard first. Make sure to split the picket so half of it is behind the existing wall board and the other half is exposed in the space where the new cement board will go. Now you can install the new cement board in the space. Screw or nail it to the studs first and now you can sink some screws into the picket behind the new cement board at the seem, sewing it together. Once this is accomplished you can now tape the joint with mess tape and slick it over with thinset.
Your now ready to tile it with your new hard goods. In doing this the joint is now inside the new tile installation, covered with tile and you won't have any drywall repair to do because it's all covered underneath the tile.