CDE 1.4.1 (and earlier) has a good quality Thai IM.
anyway, it doesn't fully support TIS-1566
(Thai Input/Output Methods for Computers) a.k.a. WTT (Wor Tor Tor).

for example, it lacks of input sequence checking.


fyi, also occurs in
CDE 1.5 (and earlier) - still has some bugs, e.g. 4711970
Netscape 7 (and earlier) - still has some bugs, e.g. 4710647, 4710930, 4711968