Question

I would like to centralize code handler for all FormClosed Event, is there a way to be notified automatically by all forms that are closing ?

Answer 1

subscribe your event handler after you instantiate the form. i.e. use +=

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

namespace Craft
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            var f = new Form2();            
            f.FormClosing += ClosingMonitorer;
            f.Show();

            var g = new Form3();
            g.FormClosing += ClosingMonitorer;
            g.Show();
        }

        void ClosingMonitorer(object sender, FormClosingEventArgs e)
        {            
            MessageBox.Show((sender as Form).Text + " is closing");
        }



    }
}

[EDIT: or you can use extension methods to simplify the event subscription process]

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

namespace Craft
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            var f = new Form2();
            f.Show(ClosingMonitorer);            


            var g = new Form3();
            g.Show(ClosingMonitorer);

        }

        void ClosingMonitorer(object sender, FormClosingEventArgs e)
        {
            MessageBox.Show((sender as Form).Text + " is closing");
        }



    }

    public static class Helper
    {
        public static void Show(this Form f, FormClosingEventHandler feh)
        {
            f.FormClosing += feh;
            f.Show();
        }
    }
}