Bug 121352 The data set binding property cannot be retrieved in report preview layout
In report preview page, the datasource/dataset property binding lists cannot be retrieved. The dataset binding can not work correctly in layout preview because it's value cannot get from the binding list. But in the data set edit page, the binding value can be got. You can refer to the attachment.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
public List getDescendents( )
	{
		ArrayList list = new ArrayList( );
		gatherDescendents( list );
		return list;
	}
	/**
	 * Builds up a list of the elements that extend from this one, directly or
	 * indirectly.
	 * <p>
	 * Part of: Inheritance system.
	 * 
	 * @param list
	 *            The list of descendents.
	 */
	public void gatherDescendents( ArrayList list )
	{
		if ( derived == null )
			return;
		for ( int i = 0; i < derived.size( ); i++ )
		{
			DesignElement child = (DesignElement) derived.get( i );
			list.add( child );
			child.gatherDescendents( list );
		}
	}
	/**
	 * Checks if the element has defined any user properties. Checks only this
	 * element, not its parents.
	 *