Woah, how massive is your screen? You're totally right though, it looks awful tiled. I'll have to take care of that.
By the way everybody, I'm working on version 2.0 which is just about a million times better than the original. Hit me up if you'd like to get beta builds and a free copy.
I'm the author of a Markdown text (prose) editor[1], and can attest to Jeff's statement that all Markdown's parsers suck. The official perl regex-based implementation is a joke. Sundown is great, but only works for cross-compilation to other markup languages; it doesn't work for syntax highlighting, which is what I'm more interested in.
I ended up writing my own in Objective-C. It's not very pretty, and it doesn't use a formal grammar (just a lexer + custom grammar code), but it does the trick. I took a few liberties with the spec: throwing in GitHub-flavored code blocks.
By the way everybody, I'm working on version 2.0 which is just about a million times better than the original. Hit me up if you'd like to get beta builds and a free copy.