Bug 136241 [regression]Preview template in web viewer and pdf didn't get correct effect.
Description: Preview template items in web viewer and pdf didn't get correct effect. Steps to reproduce: 1. Create template items. 2. Preview in Web Viewer and pdf. Expected result: Same effect as in html. Actual result: In web viewer, see only blank box. In pdf, blank page.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
*/
	public void addDisposeListener( IDisposeListener listener )
	{
		if ( disposeListeners == null )
			disposeListeners = new ArrayList( );
		if ( !disposeListeners.contains( listener ) )
			disposeListeners.add( listener );
	}
	/**
	 * Removes one dispose listener. If the listener not registered, then the
	 * request is silently ignored.
	 * 
	 * @param listener
	 *            the dispose listener to remove
	 * @return <code>true</code> if <code>listener</code> is successfully
	 *         removed. Otherwise <code>false</code>.
	 * 
	 */
	public boolean removeDisposeListener( IDisposeListener listener )
	{
		if ( disposeListeners == null )
			return false;
		return disposeListeners.remove( listener );
	}
	/**
	 * Broadcasts the dispose event to the dispose listeners.
	 * 
	 * @param event
	 *            the dispose event
	 */