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
* for the property on this element. After this, the element will now
	 * inherit the property from its parent element, style, or from the default
	 * value for the property.
	 * 
	 * @param propName
	 *            the name of the property to clear.
	 * @throws SemanticException
	 *             if the property is not defined on this element
	 */
	public void clearProperty( String propName ) throws SemanticException
	{
		setProperty( propName, null );
	}
	/**
	 * Clears values of all properties. Clearing a property removes any value
	 * set for the property on this element. After this, the element will now
	 * inherit the property from its parent element, style, or from the default
	 * value for the property.
	 * 
	 * @throws SemanticException
	 *             if the property is not defined on this element
	 */
	public void clearAllProperties( ) throws SemanticException
	{
		List props = getDefn( ).getProperties( );
		for ( int i = 0; i < props.size( ); i++ )
		{
			PropertyDefn propDefn = (PropertyDefn) props.get( i );
			setProperty( propDefn.getName( ), null );
		}