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
* @return Integer value.
	 */
	public static int getRGBInt( RGB rgb )
	{
		if ( rgb == null )
		{
			return -1;
		}
		return ( ( rgb.red & 0xff ) << 16 ) | ( ( rgb.green & 0xff ) << 8 )
				| ( rgb.blue & 0xff );
	}
	/**
	 * Gets the list of data sets which can be used for the specified element
	 * 
	 * @param handle
	 *            the handle of the element
	 * @return Returns the list of data sets which can be used for this element
	 */
	public static List getDataSetList( DesignElementHandle handle )
	{
		List dataSetList = new ArrayList( );
		if ( handle instanceof ReportElementHandle )
		{
			if ( handle instanceof ReportItemHandle )
			{
				DesignElementHandle dataSet = ( (ReportItemHandle) handle )
						.getDataSet( );
				if ( dataSet != null && !dataSetList.contains( dataSet ) )
				{
					dataSetList.add( dataSet );