public void actionPerformed(ActionEvent arg0) {
			if (arg0.getSource() == internalView.getNextMonthButton()) {
				internalModel.getModel().addMonth(1);
			} 
			else if (arg0.getSource() == internalView.getPreviousMonthButton()) {
				internalModel.getModel().addMonth(-1);
			} 
			else if (arg0.getSource() == internalView.getNextYearButton()) {
				internalModel.getModel().addYear(1);
			} 
			else if (arg0.getSource() == internalView.getPreviousYearButton()) {
				internalModel.getModel().addYear(-1);
			} 
			else {
				for (int month = 0; month < internalView.getMonthPopupMenuItems().length; month++) {
					if (arg0.getSource() == internalView.getMonthPopupMenuItems()[month]) {
						internalModel.getModel().setMonth(month);
					}
				}
			}
		}