How can I get the main form of a .NET 4 application to come to the front?

Question

I have an .NET 4 WinForm application. I have a button on the main form that opens a child form. The child form has focus. While the child form is open, if I click on the main form, the main form receives focus, but the child form remains on top of the main form.

How can I make the main form come to the front, even if the child form is open?

Here is my sample code for the two forms:

using System;
using System.Windows.Forms;

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

        private void button1_Click(object sender, EventArgs e)
        {
            var form = new Form2();

            form.Show(this);
        }
    }
}

using System.Windows.Forms;

namespace WinTest
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }
    }
}

Based on Kumar's answer below, I updated my main form as follows:

using System;
using System.Collections.Generic;
using System.Windows.Forms;

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

            _FormList = new List<Form>();
        }

        private List<Form> _FormList;

        private void button1_Click(object sender, EventArgs e)
        {
            var form = new Form2();
            form.FormClosed += Form_FormClosed;
            _FormList.Add(form);
            form.Show();
        }

        private void Form_FormClosed(object sender, FormClosedEventArgs e)
        {
            _FormList.Remove((Form)sender);
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            foreach (var form in _FormList)
            {
                form.Visible = WindowState != FormWindowState.Minimized;
            }
        }
    }
}

This now works as expected.

Answer 1

As below

Form frm = null
private void button1_Click(object sender, EventArgs e)
        {
            frm = new Form2();
            frm.Show();
        }

// Minimize issue is handled
    private void Form1_Resize(object sender, EventArgs e)
            {
                if (this.WindowState == FormWindowState.Minimized)
                {
                    frm.WindowState = this.WindowState;
                }
            }

Answer 2

Try removing the "this", and instead pass a null to the Show method.

Answer 3

Do this

form.Show(); 

instead of

form.Show(this); 

The parameter set the parent of the form to be show. A parent form will be under his child form.