Re: [css3-fonts] default font features

Robert O'Callahan wrote:

> If CSS 'letter-spacing' is greater than zero, we disable discretionary 
> ligatures, because it seems safe to assume that matches the author's 
> intent. That behavior could (and I think should) be written into the spec.

I like Adobe's approach to this in InDesign, which is to disable 
non-required ligature features if the tracking value is greater than 
+22% (expanded spacing) or -8% (condensed spacing) of the width of the 
word-space glyph in the font. Knowing this behaviour is very handy for 
those of us font developers who use contextual ligating variant glyphs 
rather than ligatures per se in our implementation of the <liga> <dlig> 
etc. features; it means we can design the overlap of those variants to 
handle some amount of expansion or contraction of spacing.

JH