RE: how to use graphic-display-p and window-system

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

> The general solution is to not try to answer the question: 
> instead, make
> sure you provide a "guaranteed" binding (i.e. a binding that only uses
> keys that are known to work pretty much everywhere),

And those are? And that is described where?

> and once that's done you may also provide another binding
> using a less standard key.

That's exactly what I'm doing. But I want to make that basic binding the
default, when the context is unlikely to not support the fancier keys.

That's why I'm looking for a general, heuristic test - likeliness, not
certainty. I'm not looking for something that is always "correct", but for a
test that lets me choose a reasonable default. Users can of course use whatever
keys they want, but a default binding that is reasonable most of the time can be
helpful.

> > 1. General colors vs no colors or limited set of colors (e.g. 256).
> 
> `display-color-cells'.
> 
> > 2. General keys vs no modifiers for keys such as TAB, insert, and
> >    prior.  This means also distinguishing between, say, C-l 
> >    and C-S-l.
> 
> Fundamentally impossible.

Are you talking about the first sentence, the second, or both?

For the first, as far as I can see, Emacs source code does this in various
places, and it seems to use `window-system' to do it. No doubt that is not 100%
accurate, but I don't need such accuracy either.

For the second, it's certainly not impossible to bind different commands to C-l
and C-S-l, if that's what you meant.