Bug 120503 Cascading Parameter can not drop into layout
Details: Cascading Parameter can not drop into layout Step: 1.Open a report design and Create a Sample Data Source and data set by "select * from CLASSICMODELS.CUSTOMERS" 2.New a cascading parameter and create CUSTOMERSNUMBER and CUSTOMERSNAME in parameter named number and name. Press OK 3.Drop parameter name into layout. Actual results: The parameter in Cascading Parameter Group can not drop to layout
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
}
	/**
	 * Gets the support list of the given parent element. The slotID is decided
	 * by the parent element.
	 * 
	 * @param parent
	 *            the parent element
	 * @return the the support list of the element
	 */
	public static List getElementSupportList( DesignElementHandle parent )
	{
		int slotID = -1;
		if ( parent instanceof MasterPageHandle )
		{
			slotID = GraphicMasterPageHandle.CONTENT_SLOT;
		}
		return getElementSupportList( parent, slotID );
	}
	/**
	 * Find the position of the element. If the element is null, the position is
	 * last
	 * 
	 * @param parent
	 * @param element
	 * @return position
	 */
	public static int findInsertPosition( DesignElementHandle parent,
			DesignElementHandle element, int slotID )
	{
		if ( element == null )