Bug 148747 Design become invalid when I extend a masterpage from Library
The attachment contains a report file and a library file. Reproduce: 1. Deploy the library("lib"), and open the report. 2. Drag Masterpage("page1") from "lib" to report. 3. Reopen the report, it become invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ExtendedItemHandle.java
* Represents an extended element. An extended item represents a custom element
 * added by the application. Extended items can use user-defined properties, can
 * use scripts, or a combination of the two. Extended items often require
 * user-defined properties.
 * <p>
 * An extended element has a plug-in property that is a name of a Java class
 * that implements the behavior for the element.
 * 
 * @see org.eclipse.birt.report.model.elements.ExtendedItem
 */
public class ExtendedItemHandle extends ReportItemHandle
		implements
			IExtendedItemModel
{
	/**
	 * Constructs the handle with the report design and the element it holds.
	 * The application generally does not create handles directly. Instead, it
	 * uses one of the navigation methods available on other element handles.
	 * 
	 * @param module
	 *            the module
	 * @param element
	 *            the model representation of the element
	 */
	public ExtendedItemHandle( Module module, DesignElement element )
	{
		super( module, element );
	}
	/**
	 * Returns the extension name defined by the extended item.