JRootPane : JRootPane « Swing « Java Tutorial

The JRootPane class acts as a container delegate for the top-level Swing containers.

14.84.2.Setting Window Decoration StyleSetting Window Decoration Style
14.84.3.Setting the default buttonSetting the default button
14.84.4.Interact directly with the JRootPane of a JFrame
14.84.5.Make a JFrame looks like a JDialog
14.84.6.Customizing JRootPane Look and Feel