When a user clicks the X on the forum to close it. I would like to ask 'are you sure you want to stop playing' before shutting down. So how can I do that?

You can add a handler for the FormClosing event to ask the user "are you sure...", setting the FormClosingEventArgs.Cancel property to true if you don't want to continue closing the form.

You can add a handler for the FormClosing event to ask the user "are you sure...", setting the FormClosingEventArgs.Cancel property to true if you don't want to continue closing the form.

This is off topic for the Visual C# Express Edition forum, moving the the Windows Forms General forum.

I made this code and it now shows 2 times the messagebox don't see why it does it twice:

  private void Form1_FormClosing(object sender, FormClosingEventArgs e)

        {

            DialogResult dlgResultStop;

            dlgResultStop = MessageBox.Show("Are you sure you want to stop playing tetris?","Stop tetris?" ,MessageBoxButtons.YesNo,MessageBoxIcon.Exclamation);

            if (dlgResultStop == DialogResult.Yes)

            {

                Application.Exit();

            }

            else if(dlgResultStop == DialogResult.No)

            {

                e.Cancel = true;

            }

        }

Extra: I would also like that all forms in my application are only able to be opened once in my application, can I use this event for it and how should I then?

thanx

If this is the main form, you don't need the call to Application.Exit(). Since the form hasn't closed yet (and won't until your return from the FormClosing handler) the application is attempting the close the form again in the Application.Exit() call; which is raising the event a second timeand asking the question again.