Sanskrit is a rich-text editor that outputs Textile instead of XHTML. See usage.
This example has not been styled, and the names for the "buttons" are the default values. These names are the same as the class names used for the list items. The dashed outline is the container for the button list and the iframe.
This example has been styled to make it look more like a normal textarea with buttons to control the styling of the text. It also replaces the default names for the buttons with new ones. This editor was created from an external Javascript file.
To get an idea of how the DOM tree is built and styled, you can have a look at the style sheet.