bug#4033: 23.1; list-colors-display is misleading

["Drew Adams" <drew.adams@oracle.com>]

> >> 16-bit RGB components is what Emacs uses internally, IIRC.  That is
> >> the reason we show each one as two letters.
> >
> > Is that right? Could you please check about this?
>   
> Emacs uses 16 bit components internally, because that is what 
> X uses in its APIs. I'm not aware of any graphics driver that allows 
> more than 8 bit granularity though, and on Windows you are restricted
> to 8 bit by the API anyway.

I'm ignorant about these things. Does that imply that Emacs does not support
#RRRRGGGGBBBB (or #RRRGGGBBB) on any systems? What is the relation between these
two 

Doesn't 16-bits per component mean 4 hex digits per component? IOW,
#RRRRGGGGBBBB (internally).

See my reply to Juri. I'd be grateful for clarification. What's the point of
having `display-color-cells' tell me that I have, say 16777216 colors available,
if that's not really the case as far as Emacs is concerned?

Consider me mixed up about this, and please set me straight. Thx.