How to solve offset overflow

[LexLuengas]

I’m working on a font with a huge amount of contextual substitutions (>14 000 substitutions). FontLab (5.1.1) refuses to compile:

Code: [Select]

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?

[LexLuengas]

Any opentype-savvy contacts you could forward to me? I know there are many geeks out there, I just don‘t know what they are called...

[Eigi]

You may try 'KLTF Make Kern Feature' from Karsten Lücke:
http://www.kltf.de/kltf_otproduction.htm

[LexLuengas]

It automatically splits large subtables into smaller ones and activates use of extension type lookups when necessary

Does the script do more than what I could do “manually” in FontLab‘s OpenType panel? And more important: Does this also work for other features other than the kern feature? Specially the splitting of the subtables sounds very luring, but I guess it just adds a subtable; statement wherever necessary.