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
DesignElement e = this;
		while ( e != null )
		{
			if ( e == element )
				return true;
			e = e.container;
		}
		return false;
	}
	/**
	 * Returns the value of a property as a number (BigDecimal).
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            the name of the property to get
	 * @return the property as a BigDecimal, or null if the value is not set or
	 *         cannot convert to a number
	 */
	public BigDecimal getNumberProperty( Module module, String propName )
	{
		Object value = getProperty( module, propName );
		if ( value == null )
			return null;
		if ( value instanceof BigDecimal )
			return (BigDecimal) value;
		ElementPropertyDefn prop = getPropertyDefn( propName );
		PropertyType type = MetaDataDictionary.getInstance( ).getPropertyType(
				prop.getTypeCode( ) );
		return type.toNumber( module, value );