Being able to use Thai in a composite font would simplify Thai layout considerably, so I created a custom character set in the composite font editor that contains the Thai block plus a few other characters used in Thai (all of the characters in Noto Sans Thai, including the zero-width spaces, etc.).
Unfortunately, when I apply the composite font to Thai text, a few of the diacritical tone marks do not display. I have tried a variety of composite font settings, to no avail.
In the composite font, the pattern seems to be that U+0E48, 0E49, and 0E4C (diacritical tones) do not display when they are directly above a character; they do display when they appear above another tone. I confirmed that these characters are in the custom set I made, and that they display fine in the same non-composite font. Is some additionally required control character needed in the custom character set?
Interesting side note, changing the font of the kanji and kana character sets changes how these non-displaying tones are displayed – i.e., the “boxes” become wider or narrower. Not sure whether this is pertinent.
System Notes: Windows 7, InDesign CC 2019 with Japanese UI exposed (in English), Adobe World Ready Composer applied. Have tried Tahoma, Noto Sans Thai, & Angsana in the composite font, all with the same results.
Thanks for reaching out. To understand this issue better, I would request if you can share some screenshots (of how it looks and how it should actually look) and a sample file. This will help us reproduce the issue at our and troubleshoot accordingly.
Thank you very much for your response and sorry for not getting back to you earlier. I must have missed your reply when I checked last month.
I'm also not seeing how to upload a file in this forum, so I simply inserted a screen shot below. Let me know if there's a way to upload the actual .indd file.
It should be fairly self-explanatory, but I'm using the composite Thai font in the 2nd paragraph and regular Thai fonts in the other two paragraphs. As best that I could, I highlighted the non-displaying characters in the paragraphs that use the regular Thai fonts.