But seriously, this was the logical conclusion, and looking at the plaster and rotten timber back there, I would have had to take it out just to eliminate pathogens. A little carpentry will do me good, anyway.
The bathtub faucet is nice, solid 1920's brass, and with some shining up it will be lovely. We destroyed one screw getting the hot-water tap off, but the reason we had to take out the wall is that (1) it was impossible to get the shower bypass valve out while the faucet was still installed and (2) right behind and to the left of the hot-water tap, somebody thought it would be a great place to put a standpipe for the bathtub drain. It was literally impossible to take the faucet out backwards, so it had to come out forwards.
The hot-water and cold-water valve bodies have been replaced (they're visibly newer); whoever did that obviously had given up on the shower bypass valve. Well, we showed that guy! Of course, he probably balked at taking out the entire wall just to fix the shower, but I really need my morning showers. And that wall and the tub surround are no loss.
So that was my plumbing diversion for the day. I thought I'd cap that off so I could get water back to the kitchen sink, but my CPVC glue dried in the can because I forgot to close the cap last time. Blocked at every turn. So maybe I'll just go destroy another window or something.
In re windows: I believe I had mentioned that my two front windows are 30"x54" with a six-inch boxed frame thing between them. The 32" replacement windows are standard at Lowe's for $138; it turns out a special-order 30" replacement window would be $195. I don't know, a hundred bucks' difference for the two windows is reason enough for me to figure out a two-inch-wide center post solution. Don't you think so?