The Dummy Frame

If a root component in your hierarchy is not a Frame, Dialog, FileDialog, Window, JFrame, JDialog or JWindow, then a Dummy Frame or Dummy JFrame (depending on whether the component is a Swing component or not) is created as a substitute to display your design. This is useful if you want to create a method which creates a component or group of components - for example, a group of labels and text fields which you wish to use again and again in your application, or you may have a Choice component which you have loaded with a list of color names which you wish to use in multiple dialogs; making the Choice a hierarchy on its own would allow you to do this.