It's object-oriented and especially designed to be extensible. The slides on the pages contain many examples. It's fairly stand-alone and isn't integrated into an IDE. However, it's small, which allows for easy implementation (see original OMeta in Smalltalk, Ometa/JS, Ometa#, etc.) and could be used as a base for implementing these IDE features.
I'd love to see a cleanup of OMeta/JS and combining it with CodeMirror.