Yes I’ve been experienced this problem since v12.0 and ONLY in WIN7 & WIN8 (winXP is working fine). And just like the OP said, in other word/text processors are working CORRECTLY, except EmEditor.
haha I thought I’m the only user that encounter with this “THAI” language problem.
FYI, for me it’s not just only for Sara Am, but it’s working INCORRECTLY for all “THAI” fonts as far as I’ve tried.
Actually, I should report this since the release of v12.0 already, but I thought it’s just only me who faced this problem and I believed it was because of my windows had problem. Now, when there is some people got the similar issue as mine, so now I’m quite sure that there must be something wrong with the Emeditor.
Hope you can fix and release the minor version very soon.
Thank you so much Yukata!!