private void menuSetDifficulty(int difficultyLevel) {
		switch(difficultyLevel) {
		case DifficultyLevel.EASY:
			this.difficultyLevel = new DifficultyLevel(DifficultyLevel.EASY);
			break;
		case DifficultyLevel.MEDIUM:
			this.difficultyLevel = new DifficultyLevel(DifficultyLevel.MEDIUM);
			break;
		case DifficultyLevel.HARD:
			this.difficultyLevel = new DifficultyLevel(DifficultyLevel.HARD);
			break;
		case DifficultyLevel.CUSTOM:
			String width =
				JOptionPane.showInputDialog("Set width (max 40)");
			String height =
				JOptionPane.showInputDialog("Set height (max 30)");
			String mines =
				JOptionPane.showInputDialog("Set amount of mines (max half of the minefield size)");
			
			if(width == null || height == null || mines == null) {
				JOptionPane.showMessageDialog(this, "Incorrect values",
						"Error", JOptionPane.ERROR_MESSAGE);
			} else {
				try {
					int intWidth = new Integer(width);
					int intHeight = new Integer(height);
					int intMines = new Integer(mines);
					this.difficultyLevel = new DifficultyLevel(intHeight, intWidth, intMines);		
				} catch(NumberFormatException e) {
					JOptionPane.showMessageDialog(this, "Incorrect values",
							"Error", JOptionPane.ERROR_MESSAGE);
				}
			}
			break;
		default:
			break;
		}
	}