bug#9054: 24.0.50; show source in other window

[Juri Linkov]

>>>> (1) Help for this object
>>>> (2) Manual entry of this object
>>>
>>> Good idea.  This should be added to emacs-lisp-mode.
>>
>> Now added.
>
> Thanks.  But to make this really useful for new users we should not talk
> about "symbols" and "identifiers" here - maybe using "this" instead
> would be better.  And we should provide some feedback when there's no
> useful information here.  Consider with
>
> (setq x 3)
>
> clicking on "x" or "3".

There is already feedback when there is no Manual entry:

  (error "Not documented as a symbol:")