> If you can find a way of fixing 17693 without disabling frameset
> restoration, feel free to do that on master.

I'm going to take a hard look at this and every frameset bug I can find. I'll revert the frameset.el and desktop.el code (locally, not on the repository) to its previous state and will try to understand the issues and the possible fixes. (I'm not implying the current fixes aren't good, only that I still don't understand their implications).

> have, I think we should not create GUI frames when Emacs is invoked
> with -nw, though, at least by default.

I don't understand this. Creating GUI frames in a -nw session shouldn't happen. "Mimicking" the GUI frames in the -nw session is what the code intended to do, so if you have three frames of whatever size and other parameters, the TTY session would start with three tty frames (F1 to F3). Then going back to GUI mode would restore the original GUI frames (not the tty ones).

> redundant, because I'd expect the following sequence of Emacs
> invocations to re-create the original GUI frames from the 1st
> invocation:
>
>   . emacs
>   . emacs -nw
>   . emacs

That is exactly what worked before (or, at least, it worked in all my tests) and it's broken now.