Bug 167542 A parameter group isn't deleted after moving it to another parameter group through DND
Drag a parameter group and drop it to another one is a "move" operation, which cuts the source and pastes to the destination. But the source one isn't deleted in such operation while the parameters in the group are all deleted.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DNDUtil.java
* 
	 * @param target
	 * @return handle of target
	 */
	public static DesignElementHandle getDesignElementHandle( Object target )
	{
		target = unwrapToModel( target );
		if ( target instanceof DesignElementHandle )
		{
			return (DesignElementHandle) target;
		}
		else if ( target instanceof SlotHandle )
		{
			return ( (SlotHandle) target ).getElementHandle( );
		}
		return null;
	}
	/**
	 * Unwraps the object to model
	 * 
	 * @param obj
	 *            object which may be wrapped, such as
	 *            <code>ReportElementModel</code>, <code>ListBandProxy</code>
	 * @return model object
	 */
	public static Object unwrapToModel( Object obj )
	{
		if ( obj instanceof ListBandProxy )
		{
			return ( (ListBandProxy) obj ).getSlotHandle( );