if ( selection.size( ) == 1 )
if ( selection != null )
	private LibraryHandle getSelectedLibrary( )	{		IStructuredSelection selection = (IStructuredSelection) viewer.getSelection( );		if ( selection.size( ) == 1 )		{			if ( selection.getFirstElement( ) instanceof LibraryHandle )			{				return (LibraryHandle) selection.getFirstElement( );			}		}		return null;	}