Here is simple panel in client mode:

RichFaces is a component library for JSF and an advanced framework for easily integrating AJAX capabilities into business applications.

- 100+ AJAX enabled components in two libraries
- r: page centric AJAX controls
- r: self contained, ready to use components
- Whole set of JSF benefits while working with AJAX
- Skinnability mechanism
- Component Development Kit (CDK)
- Dynamic resources handling
- Testing facilities for components, actions, listeners, and pages
- Broad cross-browser support
- Large and active community

And that panel switched by ajax and closed by default:

We are working hard on RichFaces 4.0 which will have full JSF 2 integration. That is not all though, here is a summary of updates and features:

- Redesigned modular repository and build system.
- Simplified Component Development Kit with annotations, faces-config extensions, advanced templates support and more..
- Ajax framework improvements extending the JSF 2 specification.
- Component review for consistency, usability, and redesign following semantic HTML principles where possible.
- Both server-side and client-side performance optimization.
- Strict code clean-up and review.