/// <summary>
        /// User clicked new project button.
        /// </summary>
        private void NewProjectButton_Click(object sender, EventArgs e)
        {
            // Browse for new project file
            SaveFileDialog dlg = new SaveFileDialog();

            dlg.DefaultExt      = ProjectDocument.Extension;
            dlg.Filter          = ProjectDocument.Filter;
            dlg.OverwritePrompt = false;
            dlg.Title           = "Create Project File";
            if (dlg.ShowDialog() != System.Windows.Forms.DialogResult.OK)
            {
                return;
            }

            // Cannot overwrite an existing project file.
            // This is to protect user from accidentally killing all their work
            // by creating instead of opening.
            if (File.Exists(dlg.FileName))
            {
                // Show error
                MessageBox.Show("Cannot overwrite existing project file.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }
            else
            {
                // Create new project file
                projectDocument.CreateProjectFile(dlg.FileName);
            }
        }