[beders]

It's a good start. However, seemingly only tested on Chrome.

After playing around with it for a few minutes, I found some issues:

On Firefox, from a Clean State, add a Row, add Text, click H2, type some text, hit space, try to type more text: the space disappears

On Chrome: I don't seem to have full control over text spans. While I can use b/I/U/S on the current text selection, I was unable to set any other style attributes just for the selected text (i.e. what should boil down to a span tag), i.e. I wanted different colors for parts of my text.

Keep on hacking and I hope you'll have success!