generate 1) virtual index and 2) other pages for Info; 3) S-mouse-2: follow link in new window

[Drew Adams]

1. It would be useful to have an Info command, say bound to `I', that would
do for index lookup what `L' (Info-history) does for chronological
navigation. You would type a regexp, and it would show you a buffer similar
to the `Recently Visited Nodes' buffer of `L'.

That buffer would have a list of all index entries that matched your regexp.
As in the existing manual indexes, it would have both the index entry (a
link) and the name of the node it occurs in. IOW, it would be a virtual
index, based on your input.

This would be useful because you would be able to simultaneously examine
multiple entries that are candidates of interest. Info-index (`i') is great,
but it doesn't give you a good picture of all matching entries, and you can
only visit them in sequence. Completion shows you all candidates that match
your input, but they are all prefix matches, which is not as useful here as
a substring or regexp match.

I know it helps to allow regexp matching and to show all matches in such a
way that you can continue to navigate among them in any order while seeing
them all, because Icicles has something similar and it is very handy.
Instead of generating a fixed buffer with links as described above, Icicles
shows you the matching index entries in *Completions*, but you can continue
to see them there as you visit their locations in the manual.

I'm not suggesting to do what Icicles does, but to do what `Info-history'
does, except with index entries.


2. The same implementation could perhaps be leveraged to let users create
their own virtual Info booklets. They would hit some key in Info nodes of
interest, and links to those nodes would be saved in an `Info-history'-like
buffer for later use. IOW, this would be like being able to save an
`Info-history' buffer. But only nodes that you select would be included in
the collection (whereas `Info-history' lists all nodes you have visited).

Yes, I know that bookmarks offer something similar, but the UI would be a
little different and this would be limited to Info nodes.


3. It would also be helpful to bind `S-mouse-2' in Info to a command that
follows an Info link in a new window. That way, a user could keep the `L' or
the `I' buffer (or a TOC or an index or any other node) open while visiting
its links in another window (or frame, with non-nil pop-up-frames).

I have used this definition:

(defun Info-mouse-follow-nearest-node-new-window (click)
    "Open the link at the mouse pointer in a new window."
    (interactive "e")
    (Info-mouse-follow-nearest-node click t)) ; t no good now

But that particular implementation no longer works, because someone over the
course of Emacs 22 development removed the optional FORK argument to
`Info-follow-nearest-node' and `Info-mouse-follow-nearest-node'. (Why?)
Regardless of how it is implemented, it would be useful. You can do the same
thing by cloning the buffer and then following a link, but it is particulaly
handy to do this with just a mouse click.