Bug 142432 MasterPage from library can't be restored to modify
Details: MasterPage from library can't be restored to modify Step: 1.New a library named lib1, and insert a masterpage named lib-mp. 2.Publish the library into resource folder. 3.New a report design and use lib1. 4.Drop the lib-mp from library explorer into outline of report design. 5.Double click lib-mp, and switch to Property editro tab. 6.Click restore. Actual result: Pop up an error message and said that the master page cannot specify size the page type is not custom.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
*            the name of the element that this one is to extend
	 * @throws ExtendsException
	 *             if no element exists with the given name, or if the element
	 *             is of the wrong type.
	 */
	public void setExtendsName( String name ) throws ExtendsException
	{
		DesignElement element = getElement( );
		ExtendsCommand cmd = new ExtendsCommand( module, element );
		cmd.setExtendsName( name );
	}
	/**
	 * Localize the element, break the parent/child relationship and set all the
	 * extended properties locally.
	 * 
	 * @throws SemanticException
	 *             the element can not be localized properly. It may be because
	 *             that the element is not extended from a parent, or that same
	 *             properties can not be localized on the element or the content
	 *             elements inside it.
	 */
	public void localize( ) throws SemanticException
	{
		DesignElement element = getElement( );
		ExtendsCommand cmd = new ExtendsCommand( module, element );
		cmd.localizeElement( );
	}
	/**
	 * Sets this element to extend the given element.
	 *