I am Creating a Ligature Base Quran Font, estimated around 22000 Glyphs. Most of the Art work is done. I am using FontLab and VOLT to create this single Font File.
I just use one OTF feature which is simple substitution method to avoid Platform & Application issues. My Ligature Length starts from 2 characters and the maximum length is 21.
I include all characters and Aeraab in my Substitution Method.
I tried this Font on Windows 7, and its working perfect on it and also try it in MS Office, Adobe, & CorelDraw, working fine. Only one issue happens in windows 7 that all Words having a length of "16 Characters" are not substituting, and showing break characters, so I change the length of all 16 characters Words to 17 length by adding a "Kashida" in it so the length goes to "17" and it works fine, so in Windows 7 All the words of length from 2 to 21 are working fine except the length of "16" characters.
Now I try my Font on windows 10, and got upset to see the result, My all Words having length from 2 to 15 are substituting fine, but all words having length of more than 16 or more are disturbing my data. Sometimes they don't substitute correctly, and sometime it substitute correctly but it disturb some other words in that Line.
Attached the Image of comparison, Words with more than 15 length are circled red, and also circle the disturbing shapes.