This looks really awesome! I really wish I could use it as a library and embed it into my SaaS app. Is there a way to extract just the rendering functionality and add it to a website?
I like that it's usable by people who want to click buttons -- and that by showing users both the formatting and the Markdown that caused it, it teaches how to skip the buttons in the future. At the same time, if you're a Markdown user doing everything on the keyboard, it's completely unobtrusive. Everybody wins.