We didn't, mostly because VS Code didn't exist yet when we added in Brackets. It got released when we were already beta testing, and was still in extreme beta by the time we officially launched the updated tool in August 2015. It would be interesting to see how many other now-existing solutions might work for the code editor part, but at this point it would disturb quite a few people who now use Thimble in the classroom or at learn-to-code events, so while as a contributor PR it would be fantastic, we don't have the man hours to investigate a completely new code editor component (with its own UI that needs tailoring, filesystem requirements, plugin infrastructure, etc).