public void undoTurn() {
this.mScores[gameState] -= addedSquares.size();
this.gameState = lastGameState;
this.lines.remove(addedLine);
drawer.removeLine(addedLine);
for (Square s : addedSquares) {
squares.remove(s);
}
drawer.removeSquares(addedSquares);
addedSquares = new ArrayList<Square>();
// disable the undo button
((Button) findViewById(R.id.undoButton)).setEnabled(false);
updateView();
}
