In learning to write Java, I like to modify the .java file, recompile,
hit the Webrunner File/Reload button and then rerun the Applet.
For the applet below, this usually gives me the following exception:

java.lang.NullPointerException
        at QueryItem.mouseUp(QueryItem.java:42)
        at webrunner.AppletDisplayItem.trackStop(AppletDisplayItem.java:438)
        at awt.DisplayItemWindow.mouseUp(DisplayItemWindow.java:396)
        at awt.Window.handleMouseUp(Window.java:185)
        at awt.WServer.run(WServer.java:65)

this happens even if I don't make a change. E.g. if I hit the reload button
and then click on the Applet.


/**
 * A simple applet class which creates a menu and does an action
 *
 * @version 1, Tue Mar 14 16:18:16 PST 1995
 */
public
class QueryItem extends Applet {

  OptionMenu menu;
  String label;
  Container container;

    /**
     * Initialize the applet.
     */
    public void init() {
        resize(100, 100);

        label = getAttribute("label");
    }

    public void paint(Graphics g) {
      container = g.drawSurface;
      g.drawString(label, width - font.stringWidth(label) - 3, height);
    }


    /**
     * The user clicked in the applet. Start the clock!
     */
    public void mouseUp(int x, int y) {
      menu.unMap();
    }

    public void mouseDown(int x, int y) {
        try {
          if (menu == null)
              menu = new OptionMenu(container, "A menu label", "a menu pname");
          menu.move(x, y);
          menu.map();
        } catch(Object e) {
        }
    }
}