RE: highlight failed part of isearch input

[Drew Adams]

> > Personally, I disagree about the color, at least for a 
> > light background with unlimited colors available - it
> > is too vivid (bright, saturated, loud). For that,
> > Plum or some other pastel is a better default, IMO.
> 
> Plum is too washed-out and weak color to indicate the error.

OK, we disagree. Maybe others, besides we two, have an opinion?

I think we want a washed-out color (Plum or another) to indicate this
"error". It should scarcely be noticeable, and it should certainly not be
distracting.

This is not about signaling some fatal error, it is about indicating a
typing mistake. I doubt most people want sirens to go off to alert them of
such a typo.

> > It's important to not only notice the failure but also 
> > easily read the text that is highlighted.
> 
> The failed search string on IndianRed1 is quite readable on a light
> background as well as on a dark background.

Again, let's try to get some more opinions on this. To me, this highlighting
should be only a subtle help - it shouldn't get in the way. And I don't find
black text on IndianRed1 to be very readable.

> > For a dark background, the color should presumably be quite 
> > dark, not bright.
> >
> > Also, I think it should specify a foreground color by 
> > default, for the case where someone uses a different
> > foreground color for a standalone minibuffer.
> 
> I think it is better to use the default foreground color,
> and if it is unreadable then the user can customize it
> to some other color that fits to user's color theme.

OK. 

But all the more reason, then, not to use the same highlight color for light
and dark background displays. And all the more reason for the highlight
color to not vary too much in value (brightness) from the default background
in each case. A pastel highlight is good for a light background, and a
darkish highlight is good for a dark background.

I don't care which hue we choose, but pastel for light background and
darkish for dark background is important, I think. We should stay away from
mid-range values.

> > How about something like this? The default color here for a 
> > dark background is the complement of Plum (a light violet):
> > a dark green. You certainly don't want something like
> > IndianRed1 or Plum on a dark background, I expect.
> 
> I'm not against selecting a more suitable color on a dark
> background, but a dark green definitely doesn't fit
> semantically and is unnoticeable.

Semantically? Do you mean fire-engine red as in "EMERGENCY!" vs green as in
"Go, it's agreen light?" ;-)

Looking for semantics in the color used here is stretching it. Better to
just look for something that works visually: dark enough, but not too dark,
etc. 

I don't care which hue (green, red, blue, magenta, cyan, yellow) we use, but
the difference in value (brightness) from the normal background should be
slight - noticeable, but slight.

> > BTW - I'm no expert on face specs, but isn't your 
> > duplication of the red spec for (min-colors 8) and
> > (min-colors 16) redundant? Doesn't (min-colors 8),
> > as shown above, take care of both?
> 
> I don't know a reason for this duplication.  I took the 
> definition from the `isearch' face that has this duplication.

Hm. Maybe someone who is wise in these things can light our lanterns.