Bug 122850 Table/list should not be able to be inserted in Master Page mode.
Description: Table/list should not be able to be inserted in Master Page mode. Steps to reproduce: 1. New a report and transfer to Master Page mode. 2. New a datasource and dataset 3. Drag a list/table to page header/footer, bind it to dataset and drag some columns inside. 4. Save and preview Expected result: Insert list/table item in master page should be forbidden. Actual result: They are allowed and preview showed "undefine" in page
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* a pointer to the target structure itself.
	 * 
	 * @param oldRef
	 *            the old reference, if any
	 * @param newRef
	 *            the new reference, if any
	 * @param prop
	 *            definition of the property
	 */
	protected void updateReference( StructRefValue oldRef,
			StructRefValue newRef, ElementPropertyDefn prop )
	{
		ReferencableStructure target;
		
		
		if ( oldRef != null )
		{
			target = oldRef.getTargetStructure( );
			if ( target != null )
				target.dropClient( this );
		}
		
		
		
		if ( newRef != null )
		{
			target = newRef.getTargetStructure( );
			if ( target != null )
				target.addClient( this, prop.getName( ) );
		}