I think the implementation is worth taking a look at. Follow the link for details, a screencast (4 min), and download. (this is paid feature, but there is a no signup 7 day trial so you can play with it)

In the past I have used plain text formats (like .taskpaper and .markdown) for my apps. I've grown sick of seeing and parsing syntax characters, so this time around I am taking a rich text approach.

Rich text looks clean, but editing is problematic. You don't have precise control/visibility into the formatting. It's hidden behind the text. There are no formatting characters to guide you like you have in Markdown. This is particularly problematic when you want to insert text at formatting boundaries.

Bike solves this with "typing affinity". This lets you precisely specify which formatting to use at those boundaries. It does this by adding an extra text caret state at these boundaries. This extra state allows you to point the text caret upstream or downstream to the formatting you want.

Other interesting features include:

• Link Buttons: Insert a dedicated "open" button after each link so there is no conflict between editing link text and opening the link.

• Keyboard Centric Formatting Popover: Remember a single keyboard shortcut and have full keyboard access to formatting commands. No mouse needed.

• Visible Typing Attributes: Show hidden typing attribute state (when it cannot be visually determined by looking at surrounding text) as part of the text caret.

Please take a look and let me know what you think. I'm happy to answer questions and would love to hear your thoughts on ways to improve rich text editing further.