[yukinon]

This looks really great, and I had fun playing around with it.

One small thing that stuck out: there isn't any way to make a newline. You have to make an entirely new comment. Or is there some shortcut key I'm missing? On a lot of text editors, it's Shift + Enter.

[ryanlbrown]

You're right. We chose not to allow hand-wrapped paragraphs because the newlines have no effect on the resulting rendered HTML. In some cases, it will allow newlines (lists, blockquotes).

[sigsergv]

It would be great to autoindent next line when writing code blocks (that start with 4 space, for example).

[julianlam]

Sounds like you're looking for tabIndent.js

[jkrems]

It was one of the first things I tried and it immediately disturbed the normal flow. Markdown normally allows for a "one line per sentence"-style. If you are used to that, the current behavior quickly becomes annoying.

[McGlockenshire]

This breaks simple things, like trying to do multiple lines of four-space indented code formatting, for example.

It also breaks trying to type out quotes and nested quotes.