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
{
			account = account + 1;
			itor.next( );
		}
		return account;
	}
	/**
	 * Get default slot id of give container element
	 * 
	 * @param parent
	 * @return slot id, -1 if not found
	 */
	public static int getDefaultSlotID( Object parent )
	{
		int slotID = -1;
		if ( parent instanceof GraphicMasterPageHandle )
		{
			slotID = GraphicMasterPageHandle.CONTENT_SLOT;
		}
		else if ( parent instanceof ParameterGroupHandle )
		{
			slotID = ParameterGroupHandle.PARAMETERS_SLOT;
		}
		else if ( parent instanceof ReportDesignHandle )
		{
			slotID = ReportDesignHandle.BODY_SLOT;
		}
		else if ( parent instanceof LibraryHandle )
		{
			slotID = ModuleHandle.COMPONENT_SLOT;