How do I Change the CSS on a tooltip?

Is it possible at all, or do I need to write my own tooltip system?

If you want to use CSS, create your tooltip from a form element object such as list (list box), textbox, or button object, and style as required.

Otherwise, use a 9patch/sprite/tiledbackground with text/spritefont object together in a container.

Thanks, but presumably this would not effect the tooltip option that C3 has for its own object>properties/tooltip. What you describe just sounds like I'd need to create my own popup code. Is that correct?