Possible Duplicate:
WMD unable to render markup inside words
Bolding words that include an underscore doesn't work
If in a Stack Overflow question or answer text area I write
unchanged
and then attempt to emphasise the 'un' prefix, by selecting those two letters and pushing the 'I' button on the toolbar, it just shows up as
unchanged
Of course, I'd expect the italic button to give me some syntax that renders as
unchanged