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
assert currentRoot != null;
			
			value = e.getPropertyFromSelf( currentRoot, prop );
			if ( value != null )
				return value;
			e = e.getVirtualParent( );
		}
		return value;
	}
	/**
	 * Returns the property value from this element. The value is only from
	 * local properties or local style of this element.
	 * 
	 * @param module
	 *            the module
	 * @param prop
	 *            the definition of property
	 * @return the property value, or null if no value is set.
	 */
	protected Object getPropertyFromSelf( Module module,
			ElementPropertyDefn prop )
	{
		
		Object value = getLocalProperty( module, prop );
		if ( value != null )
			return value;
		
		StyleElement style = getStyle( module );
		if ( style != null )
		{