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

[Drew Adams]

> > I have had at least one user state that he thought that, since the
> > form shown is #RRGGBB, his colors had only that granularity.  IOW,
> > even if one's system allows colors of the form #RRRRGGGGBBBB (more
> > colors), the color names are translated to hex strings of the form
> > #RRGGBB (fewer colors).
> 
> Could you show a formula that calculates the color granularity?
> 
> We could use it to print colors in the short format #RRGGBB
> for the smaller color space and #RRRRGGGGBBBB otherwise.

Dunno. I'm really no expert on this.

But IIUC `display-color-cells' gives info about the color depth / number of
colors supported by the display. I was assuming that whatever the display
supports Emacs would support too, but maybe that's a mistaken assumption.

So I was assuming that `display-color-cells' would indicate the number of colors
available (supported). Then, based on that I figured we should be able to know
how many hex digits to use for each component.

Maybe I'm wrong (it's beginning to sound like it), but that's how I was
thinking. Again, I know nothing about this stuff. It's quite likely I'm
confusing apples and oranges. Thanks to whoever clarifies this for me.