FlexDock is a Java docking framework for use in cross-platform 
 Swing applications. It offers features you'd expect in any desktop
 docking framework such as:
 
    * Tabbed and Split Layouts
    * Drag-n-Drop capability (with native drag rubber band painting
      on some platforms)
    * Floating windows
    * Collapsible Containers to Save Real Estate
    * Layout Persistence

WWW:	https://flexdock.dev.java.net/