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 design element handle to check
	 * 
	 * @return <code>true</code> if the slot with the given
	 *         <code>slotId</code> can contain the <code>content</code>,
	 *         otherwise <code>false</code>.
	 * 
	 * @see #canContain(int, String)
	 */
	public boolean canContain( int slotId, DesignElementHandle content )
	{
		if ( content == null )
			return false;
		boolean flag = getElement( ).canContain( getModule( ), slotId,
				content.getElement( ) );
		if ( !flag )
			return false;
		return !getModule( ).isReadOnly( );
	}
	/**
	 * Returns the semantic error list, each of which is the instance of
	 * <code>ErrorDetail</code>.
	 * 
	 * @return the semantic error list.
	 */
	public List getSemanticErrors( )
	{
		List exceptionList = getElement( ).getErrors( );
		if ( exceptionList == null )
			return Collections.EMPTY_LIST;
		List errorDetailList = ErrorDetail.convertExceptionList( exceptionList );