Yutaka wrote:
1) The spelling checker was analyzed by the spelling engine (Hunspell), so it is separate from EmEditor. Currently, there is no easy way to make an underscore (‘_’) a part of a word unless modifying the Hunspell source code or the spelling data.

Can’t EmEditor scan the text for words and just pass them to Hunspell for checking, and then underline based on the return value from Hunspell?

This way EmEditor has full control over what’s considered a word or not.