private void handleBack() {
		Game game = pgnViewer.getGame();
		Turn turn = game.getCurrentTurn();
		pgnViewer.undoCurrentTurn();
		for (GameStateChange gameStateChange : turn.getGameStateChanges()) {
			if (gameStateChange instanceof Move) {
				Move move = (Move) gameStateChange;
				if (move.getDestination() == null) {
					addChessPiece(move.getStart(), move.getChessPiece());
				} else {
					moveChessPiece(move.getDestination(), move.getStart());
				}
			}
		}
	}