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
* Determines if this element can be dropped from its container.
	 * 
	 * @return <code>true</code> if it can be dropped. Returns
	 *         <code>false</code> otherwise.
	 */
	public boolean canDrop( )
	{
		
		
		if ( isRootIncludedByModule( ) )
			return false;
		
		
		if ( isVirtualElement( ) )
			return false;
		
		
		if ( container instanceof TemplateParameterDefinition )
		{
			assert containerSlotID == TemplateParameterDefinition.DEFAULT_SLOT;
			return false;
		}
		
		
		
		DesignElement element = this;
		if ( element instanceof TemplateParameterDefinition )
		{
			List clients = ( (TemplateParameterDefinition) element )
					.getClientList( );