I posted an answer on english.SE in which I wanted to type an 'n' with a dot below. Using the actual character
- LATIN SMALL LETTER N WITH DOT BELOW (U+1E47, HTML ṇ) (test word: varṇa / varṇa)
looked ugly in the serif-font used there. It seemed (in preview) to be displaying that character in a different font, probably because the default font didn't have this character.
so I instead used, after n, the character
- COMBINING DOT BELOW (U+0323, HTML ̣) (test word: varṇa / varṇa)
This appeared fine in preview (same font as the rest of the text). But when I hit Post, the character in the answer had changed into the pre-composed 'n with dot below' (U+1E47), which was ugly.
Why this transformation? Implementing this current behaviour seems it would take more effort than leaving the characters as they were, so I'm not even sure whether this is a StackExchange-specific bug or part of some Unicode implementation. Anyway, why does this change happen?
Edit: Browser: Google Chrome 8.0.552.237 on Mac OS X 10.6.6. The possibility just occurred to me that Chrome may be submitting 'ṇ' when I type 'ṇ', in which case it wouldn't be a StackExchange-specific bug, but I'd like to hear from someone who knows the issue better. (I can't thoroughly test it myself on any Stack Exchange site without bumping up posts. :p)
Edit2: It's repeatably happened in this post itself, where in the first "test word" for using the combining character I type the two-character version (n followed by U+0323) but after posting it turns into the former (the character U+1E47). The second 'test word', which I type using the HTML entity, is not affected.
Edit3: In the default font used for meta.SO (Arial), the two forms look alike. Please try a font like Georgia (the default on english.SE) to see the difference. The link to the original post is here, in case it helps.