Use a JFrame bean
to provide a desktop window with a title bar, sizing borders, and sizing
buttons. You can add beans to the frame and its content pane to define
menus and other user interface components.
The JFrame bean provides a content pane in which to place other components. The content pane provides logical separation of the frame from its child components. With the exception of a JMenuBar, user interface components are added to the content pane. The default content pane, a JFrameContentPane, is represented in the Beans List as the child of the JFrame bean. You can delete the default content pane and replace it with another container component.
Use a Frame bean, rather than a JFrame bean, if you want to use AWT components in the frame.
Composing a window
Sun's JFrame bean documentation
JInternalFrame (Swing)
Window beans
Beans for visual composition