Cancel window closing event : Window Event « Windows Presentation Foundation « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Windows Presentation Foundation
3. Window Event

using System;
using System.ComponentModel;        // for CancelEventArgs
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;

    class MainClass : Window
    {
        static string strFileName = "c:\\a.txt";
        TextBox txtbox = new TextBox();
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new MainClass());
        }
        public MainClass()
        {
            txtbox.AcceptsReturn = true;
            txtbox.TextWrapping = TextWrapping.Wrap;
            txtbox.VerticalScrollBarVisibility = ScrollBarVisibility.Auto;
            txtbox.KeyDown += TextBoxOnKeyDown;
            Content = txtbox;

            txtbox.Text = File.ReadAllText(strFileName);
            txtbox.CaretIndex = txtbox.Text.Length;
            txtbox.Focus();
        }
        protected override void OnClosing(CancelEventArgs args)
        {
            try
            {
                Directory.CreateDirectory(Path.GetDirectoryName(strFileName));
                File.WriteAllText(strFileName, txtbox.Text);
            }
            catch (Exception exc)
            {
                MessageBoxResult result = 
                    MessageBox.Show("File could not be saved: " + exc.Message + 
                                    "\nClose program anyway?", Title, 
                                    MessageBoxButton.YesNo, 
                                    MessageBoxImage.Exclamation);

                args.Cancel = (result == MessageBoxResult.No);
            }
        }
        void TextBoxOnKeyDown(object sender, KeyEventArgs args)
        {
            if (args.Key == Key.F5)
            {
                txtbox.SelectedText = DateTime.Now.ToString();
                txtbox.CaretIndex = txtbox.SelectionStart + txtbox.SelectionLength;
            }
        }
    }

24.71.Window Event
	24.71.1.	Window mouse down event
	24.71.2.	Window Preview mouse down event
	24.71.3.	Window mouse up event
	24.71.4.	Window.DragMove
	24.71.5.	Window.CommandBindings
	24.71.6.	Use Window Activated and Deactivated event to control a media file
	24.71.7.	Custom Element Binding Window
	24.71.8.	ShutdownMode.OnLastWindowClose
	24.71.9.	Window Loaded event
	24.71.10.	Close a window with Escape key pressed
	24.71.11.	Window Closing and Closed event
	24.71.12.	Create Window and add window closing event handler
	24.71.13.	Do not handle events until Window is fully initialized.
	24.71.14.	Window On Mouse move event
	24.71.15.	Window On Mouse up event
	24.71.16.	Window Preview Key Events
	24.71.17.	Listen to Window loaded event
	24.71.18.	Listen to window resize event
	24.71.19.	Retrieving the mouse position relative to controls on a Window
	24.71.20.	Listen to text input event for Window
	24.71.21.	Get input text from TextCompositionEventArgs.Text
	24.71.22.	Cancel window closing event