Problem to help

[Claudio Luz]

Dear javaranchs,
I am testing my application. I am noting that when
i move the mouse over of the JEditorPanel occurs
the following error message:
I implemented HelpViewer.java like a JFrame that
uses JEditorPane to shows the contents of help.
java.lang.NullPointerException
at javax.swing.text.html.HTMLEditorKit$LinkController.doesElementContainLocation(Unknown Source)
at javax.swing.text.html.HTMLEditorKit$LinkController.mouseMoved(Unknown Source)
at java.awt.AWTEventMulticaster.mouseMoved(Unknown Source)
at java.awt.Component.processMouseMotionEvent(Unknown Source)
at javax.swing.JComponent.processMouseMotionEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

My HelpViewer is launched in DataController.java

  
        dataView.helpAction( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
               if ( ( helpOnLine != null )
                   && ( helpOnLine.isDisplayable())) {
                          return;
               }
               helpOnLine = new HelpViewer();
               helpOnLine.setTitle("Help on line about fly by nigh services");
               helpOnLine.setVisible( true );
            }
        });

DataController is a simple class like
public DataController {
// bla bla
}
By the way, i am using the version 1.4.0-b92,
some suggestion to clean that problem?
Thanks in advance.