bug#1322: dedicated *Help* and M-x help-for-help

[martin rudalics <rudalics@gmx.at>]

 > I'm not sure this will be sufficient. Remember that help-for-help
 > has entries that bring up info, NEWS, etc. Now if *Help*
 > is the only thing in special-display-buffer-names and
 > help-for-help is in it's own frame, accessing these help
 > functions through help-for-help is going to spawn another frame.
 >
 > To see this:
 >
 >   emacs -Q
 >   M-: (setq special-display-buffer-names '("*Help*"))
 >   f1 f1 C-a
 >   Return to first frame
 >   f1 f1 C-n
 >
 > Now there's four frames open!

Yes.

 > Surely this is not the intended
 > behaviour of help-for-help, even after fixing the iconification
 > issue.

It is.  `special-display-popup-frame', for whatever reason, has

   (set-window-dedicated-p (frame-selected-window frame) t)

so C-a and C-n are not allowed to use the help window because they do
not put their information into *Help*.

 > One way to work around that is to restrict help-for-help to the
 > original frame in some way. If that is not acceptable then
 > shouldn't we at least make sure that the user's commands are
 > taking effect in the correct frame? It doesn't seem right that a
 > help command will display differently when you run it through
 > help-for-help.

We'd have to write our own `special-display-function' for that.

martin