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
}
	/**
	 * Applies a design visitor. The derived element calls the corresponding
	 * visitMumble( ) method in the visitor. The visitor allows an algorithm to
	 * be implemented in a single visitor class, rather than all across the
	 * element inheritance hierarchy.
	 * 
	 * @param visitor
	 *            The visitor to apply.
	 */
	public abstract void apply( ElementVisitor visitor );
	/**
	 * Gets a property converted to a string value.
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            The name of the property to get.
	 * @return The property value as a string.
	 */
	public String getStringProperty( Module module, String propName )
	{
		ElementPropertyDefn prop = getPropertyDefn( propName );
		if ( prop == null )
			return null;
		Object value = getProperty( module, prop );
		if ( value == null )
			return null;
		return prop.getStringValue( module, value );
	}