When working with complex documents, it would be helpful to have a free text field for each paragraph and character style. I imagine using this field to describe how and when to use each style in the document. In many professional settings, this is usually done in a separate style guide document but that requires separate programs and windows to be open, where as this would allow the information to be presented and referenced as close as possible to where it is needed. In cases where a style guide exists, the field could be a page or paragraph reference back to that larger document.

I imagine the first 100 characters or so being presented in a tooltip when the user hovers over a style name in the panel and the full content shown when the edit style dialog is opened.