Re: ElDoc: adding optional support to display messages in header-line instead of the echo area

[martin rudalics]

> can you explain why? I put the omessage into the ELSE block because
> somebody on emacs-help suggested it and it made sense to me at that
> time.

Compiling eldoc.el after applying your patch gets me

eldoc-new.el~:550:1:Warning: the function `omessage' is not known to be
    defined.

This happens because in the

      (cond (eldoc-last-message (if eldoc-display-in-header-line
                                    (setq header-line-format eldoc-last-message)
                                  (message "%s" eldoc-last-message)
                                  (omessage (message nil)))))))

form you misplaced the parentheses and thus `omessage' is not considered
a condition of some clause of the `cond' special form but as a function
call.

BTW, I suppose you also need to call `force-mode-line-update' because
Emacs does not necessarily update the contents of the header line when
just moving point.

martin