bug#45072: 28.0.50; Emacs switches other buffer back uncontrollably, if other window's buffer is changed by user during minibuffer editing

[martin rudalics]

>> It seems that problem is that read_minibuf messes up the windows so much,
>> that at the end currently the only way to fix this mess is by restoring
>> the previous window configuration.  This means that there is a need
>> to fix read_minibuf to restore all previous window states without using
>> restore_window_configuration.  Only then it will be possible to add
>> a user option to disable using restore_window_configuration.
>
> But without such an option, it's hard to find and fix the problems,
> because they're hidden by the `restore_window_configuration`.
> So maybe we should introduce such an option, and then force ourselves to
> live with it and then fix the problems we encounter.

Exiting from and quitting `read-minibuffer' is hairy, in particular with
multiple frames.  IIRC it's hard to tell for an application how to clean
up the state when the user quits and throws it back to the top level.

martin