The JApplet bean
differs in one way from the AWT Applet bean in that it contains a content
pane. In the Visual Composition Editor this content pane completely
covers the JApplet bean. While the content pane provides logical
separation of the applet from its child components, it also makes accessing
the JApplet bean difficult. You can, however, access the JApplet bean
within the Beans List. With the exception of a JMenuBar, you add user
interface components to the content pane. The default content pane,
JAppletContentPane, is represented in the Beans List as the child of the
JApplet bean. You can delete the default content pane and replace it
with another container component.
If you want to create an applet using Swing components, specify JApplet as the superclass for a new applet bean.
If you want to use AWT components in the applet, use an Applet rather than a JApplet bean.
Composing an applet
Sun's JApplet class documentation
Applet beans
Beans for visual composition