/// <summary>
        /// Clear random number list and generate new numbers.
        /// Random number list is made visible if it's not already visible.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void generateButton_Click(object sender, EventArgs e)
        {
            this.updateGUI(DisplayModes.Generating);

            int lowRange = Convert.ToInt16(lowestNumberNumericUpDown.Value);
            int highRange = Convert.ToInt16(highestNumberNumericUpDown.Value);
            int listSize = Convert.ToInt16(numberOfRandomNumbersNumericUpDown.Value);

            // initialize Randomness and generate the numbers
            Randomness randomListGenerator = new Randomness(lowRange, highRange, listSize);
            int[] numberList = randomListGenerator.generate();

            // clear list box
            randomNumberListBox.Items.Clear();

            // popluate list
            for (int i=0; i<numberList.Length; i++)
            {
                randomNumberListBox.Items.Add(numberList[i]);
            }

            this.updateGUI(DisplayModes.Generated);
        }
        /// <summary>
        /// Clear random number list and generate new numbers.
        /// Random number list is made visible if it's not already visible.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void generateButton_Click(object sender, EventArgs e)
        {
            this.updateGUI(DisplayModes.Generating);

            int lowRange  = Convert.ToInt16(lowestNumberNumericUpDown.Value);
            int highRange = Convert.ToInt16(highestNumberNumericUpDown.Value);
            int listSize  = Convert.ToInt16(numberOfRandomNumbersNumericUpDown.Value);

            // initialize Randomness and generate the numbers
            Randomness randomListGenerator = new Randomness(lowRange, highRange, listSize);

            int[] numberList = randomListGenerator.generate();

            // clear list box
            randomNumberListBox.Items.Clear();

            // popluate list
            for (int i = 0; i < numberList.Length; i++)
            {
                randomNumberListBox.Items.Add(numberList[i]);
            }

            this.updateGUI(DisplayModes.Generated);
        }