bug#19395: 25.0.50; Setting left fringe to 0 messes up window-width

[martin rudalics]

>> The faces apparently _get_ merged dependent on the buffer _and_ the
>> frame.
>
> Remapped faces might depend on the buffer

... and the frame ...

> , non-remapped ones depend
> only on the frame.
>
>> I need a corresponding `window-char-height' as well, probably also with
>> a FACE argument.
>
> Without the FACE argument, you already have default-font-height,

It's the window that establishes the correspondence between a buffer and
its frame.  Otherwise we can do away with `window-char-width' as well.

>> I profoundly dislike the "default-" prefix here.  `buffer-font-height'
>> and `buffer-font-width' would be much better IMHO.
>
> But a buffer can use a variety of fonts.

OK.  Then this needs a better doc-string.

martin