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
* @param module
	 *            the module
	 * @param container
	 *            the container element
	 * @param slotId
	 *            the slot id of the container element
	 * @param defn
	 *            the element definition
	 * @return <code>true</code> if this insertion is valid. Otherwise
	 *         <code>false</code>.
	 */
	protected List checkContent( Module module, DesignElement container,
			int slotId, IElementDefn defn )
	{
		return new ArrayList( );
	}
	/**
	 * Returns the slot within the container element that holds this element.
	 * 
	 * @return the container's slot in which this element appears
	 */
	public int getContainerSlot( )
	{
		return containerSlotID;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.core.IPropertySet#getObjectDefn()
	 */