[HarfBuzz] Multiple substitution and mark positioning

[Jonathan Kew]

On 25/7/12 22:13, Khaled Hosny wrote:
> This only applies to the marks that result of multiple substitution i.e.
> in Amiri the middle lam of لله is substituted with
> <lam><shadda><smallalef>, I don’t think Arabic Typesetting has something
> like that.
>

Just wondering (without checking the code yet...) - is it possible that 
we're failing to set the glyph category from GDEF properly for marks 
that are inserted by GSUB rules like this, and as a result the GPOS 
lookups don't match as expected?