Bug 145991 [Regression]Invalid data set should not be allowed to drag or "Insert in layout"
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DataSetHandle.java
{
		/**
		 * Constructs the handle for a top-level property with the given element
		 * handle and the definition of the property.
		 * 
		 * @param element
		 *            a handle to a report element
		 * @param prop
		 *            the definition of the property.
		 */
		public DataSetParametersPropertyHandle( DesignElementHandle element,
				ElementPropertyDefn prop )
		{