I’m working on a font with a huge amount of contextual substitutions (>14 000 substitutions). FontLab (5.1.1) refuses to compile:
GSUB feature 'ˇˇˇˇ' causes overflow of offset to a subtable (0x10008)
I already added the useExtension directive to all of the lookups. The compiler doesn’t complain only if I include less than about 3500 of the lines of code.
I examined the behavior under FontLab 5.0.4, in which I can include much more substitutions if I separate my lookups into dummy features, each feature having about 3000 lines. This works only up to two extra features.
Any hints of what I should try out next?