Goal:
Save a notepad file in the computer. (C#)

Problem:
I don't know how to make a preselection as "TXT Files(*.txt)" in the "Save as type:" when save dialog display?

// Fullmetalboy

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace Labb2_application
{
    public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent();
        }

        private void mnuFileOpen_Click(object sender, EventArgs e)
        {

            OpenFileDialog fDialog = new OpenFileDialog();
            fDialog.Title = "Öppna";
            fDialog.Filter = "Text files|*.txt";
            fDialog.InitialDirectory = @"C:\Windows";
            fDialog.ShowHelp = true;

            DialogResult result = fDialog.ShowDialog(); // Show the dialog and get result.

            if (result == DialogResult.OK)
            {
                string fileAdress = fDialog.FileName;

                try
                {
                    string textContent = File.ReadAllText(fileAdress);

                    rtxtDisplay.Text = textContent;
                }
                catch (IOException)
                {


                }



            } // If syntax

        }


        private void mnuFileSave_Click(object sender, EventArgs e)
        {
            saveAsFileDialog.ShowDialog();
        }






        private void mnuFileSaveAs_Click(object sender, EventArgs e)
        {

            saveAsFileDialog.Filter = "Text files|*.txt";
            saveAsFileDialog.ShowDialog();

        }


        private void mnuFileExit_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }


        private void saveAsFileDialog_FileOk(object sender, CancelEventArgs e)
        {
            string fileNameAddress = saveAsFileDialog.FileName;

            File.WriteAllText(fileNameAddress, rtxtDisplay.Text);
        }










    } // Partial Class
}