LazyPanel and LazyContent is something I'm moving into WebLaF from one of our proprietary projects. These two features were made to provide a streamlined and easy way of asynchronously loading data (or performing any long calculations in general) and displaying related UI elements afterwards.

While there is SwingWorker provided in Swing - we simply found it lacking functionality that is often needed (container management, progress display, different loading trigger events etc).

I'll post more information on these features once they're out.