Re: isearch multiple buffers

[Richard M Stallman]

    whose single input argument accepts a list of files/buffers to search.
    They then switch to the first file/buffer from this list and start
    Isearch in it.

It sounds good.  But I would like to point out that you are developing
yet another way of specifying a set of buffers and then acting on
those buffers.  In this case, the only kind of action is to search
them, at least so far.  Maybe others could be added.

There are other features of this general sort.  One of them is
filesets.  It was meant to provide a general solution for this kind of
thing, but it does not seem to have caught on much.  Perhaps it is not
smoothly enough integrated with the rest of Emacs.

Since you're starting on a new one, I wonder if you could turn this
into a convenient interface for doing various operations on the same
set of buffers.  If we succeed in doing this, once and for all, it will
be a major stap forward.