This applet tests two custom components, MirrorLabel and MirrorLabel . It also tests the validate() method. The user can click a button to change the text on the components in the applet. Clicking another button will validate the applet. This will cause components that have been invalidated to be resized. The MirrorLabel is automatically invalidated when its text is changed. For the StopWatch and Buttons, it might be platform-dependent.