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
}
		else if ( parent instanceof CellHandle )
		{
			slotID = CellHandle.CONTENT_SLOT;
		}
		else if ( parent instanceof RowHandle )
		{
			slotID = RowHandle.CONTENT_SLOT;
		}
		else if ( parent instanceof GridHandle )
		{
			slotID = GridHandle.ROW_SLOT;
		}
		else if ( parent instanceof ThemeHandle )
		{
			slotID = ThemeHandle.STYLES_SLOT;
		}
		return slotID;
	}
	/**
	 * Get the slot id of child
	 * 
	 * @param parent
	 * @param child
	 * @return slot ID
	 */
	public static int findSlotID( Object parent, Object child )
	{
		assert parent instanceof DesignElementHandle;
		assert child instanceof DesignElementHandle;