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
* created and not yet added to the design.
	 * 
	 * @param child
	 *            handle to the newly created element
	 * @param slotId
	 *            slot id in which the child item will be added.
	 * @throws ContentException
	 *             if the element is not allowed in the slot
	 * @throws NameException
	 *             if the element has a duplicate or illegal name
	 * 
	 */
	public void addElement( DesignElementHandle child, int slotId )
			throws ContentException, NameException
	{
		SlotHandle slotHandle = getSlot( slotId );
		if ( slotHandle != null )
			slotHandle.add( child );
	}
	/**
	 * Returns the methods defined on the element definition.
	 * 
	 * @return List contains the methods.
	 * 
	 */
	public List getMethods( )
	{
		return getElement( ).getDefn( ).getMethods( );
	}
	/**