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 Module getRoot( )
	{
		DesignElement element = this;
		while ( element.getContainer( ) != null )
			element = element.getContainer( );
		if ( element instanceof Module == false )
			return null;
		return (Module) element;
	}
	/**
	 * Implements to broadcast an event to all listeners of this design element.
	 * Implementations of sendEvent( ) call this to do the actual work of
	 * broadcasting.
	 * <p>
	 * Part of: Notification system.
	 * 
	 * @param ev
	 *            the event to send
	 */
	public final void broadcast( NotificationEvent ev )
	{
		if ( this instanceof Module || getContainer( ) != null )
			broadcast( ev, getRoot( ) );
	}
	/**
	 * Implements to broadcast an event to all listeners of this design element
	 * on a design tree. Note subclasses should override this method to change
	 * the behavior of broadcast method.
	 * 
	 * Part of: Notification system.