bug#22757: 25.1.50; `face-at-point` and `faces--attribute-at-point` -- add argument WINDOW-OR-BUFFER

[Keith David Bershatsky <esq@lawlist.com>]

I spent a few hours trying to figure out how to obtain face properties at various points (with no active region) when active region was covering up those areas in another window displaying the same buffer in a different frame (hidden visually behind other frames).  It was even more complicated to track down because the default value of `highlight-nonselected-windows` is `nil` and I couldn't visually see what was happening.  I eventually discovered that third argument to `get-char-property` and my dilemma was resolved.  :)

Another helpful feature would be an optional argument for POINT so that a user does not need to goto that point in order to obtain the face(s).

Feature request #22757 *may potentially* save other people hours of debugging; and, I believe adding POINT and WINDOW-OR-BUFFER as optional arguments could be very useful by making the current functions more powerful/versatile.

BACKGROUND:  I am working on converting to C (from Lisp) a custom `color-vector-calc` function that returns the three digit color code at a given point in a window.  Now that I discovered the third argument to `get-char-property`, I have a working function in Lisp.

Keith

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At Sun, 21 Feb 2016 22:54:07 +0200,
Eli Zaretskii wrote:
> 
> * * *
> 
> Why can't you call get-char-property directly?  face-at-point is
> nothing more than a thin wrapper around get-char-property, and most of
> the wrapper code is about stuff you don't care about AFAIU from your
> description.
> 
> Is there something I'm missing?
> 
> Thanks.