To confirm the behavior of the applet, double click the applet in the Contents pane and select "Preview Applet" from the menu that appears by right-clicking.
The Applet Viewer (browser) starts and the applet is reproduced. If the Applet Viewer fails to start, select "Tool" -> "Options" from the menu, and then click [Other Applications] button on the [Application] Tab. You can make the necessary settings for [Applet Viewer] in the displayed dialog.