public ImageIcon getThumbnail( Picture p ) { return getThumbnail( p.getSource().getPath() );
public ImageIcon getThumbnail( String filename ) { if ( filename == null ) { return null; }  ImageIcon r = thumbnailCache.getThumbnail( filename );  if ( r == null ) { r = defaultThumbnail; }  return r;
	public ImageIcon getThumbnail( Picture p ) {		return getThumbnail( p.getSource().getPath() );	}