bug#9054: 24.0.50; show source in other window

[Juri Linkov]

>> We desperately need to separate the help back-end from its presentation 
>> layer.
>> The back-end should collect information and return it as alists.
>
> Why as alists?  Who would generate the buffer text?

The back-end should return collected data as alist,
and front-end should render data as the buffer text.

>> it will show 3x3 items:
>>
>>    "Find Definition"
>>    "Find References"
>>    "Back Definition"
>>    "Find Definition in another window"
>>    "Find References in another window"
>>    "Back Definition in another window"
>>    "Find Definition in another frame"
>>    "Find References in another frame"
>>    "Back Definition in another frame"
>
> Agreed.  Although "Back Definition" should already know the window it
> should act upon.  So maybe use some modifier for the "another" window
> click and explain it in the tooltip (which, IIRC we do not always show
> on Windows).

Indeed, now there are such modifiers: ‘C-x 4 0’ and ‘C-x 4 4’.