Example: Multi Document Interface

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;

namespace WinForms7
{
    public partial class MidParent : Form
    {
        public MidParent()
        {
            InitializeComponent();
        }

        private void form1ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form1 f = new Form1();
            f.MdiParent = this;
            f.Show();
        }

        private void arrangeIconsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.ArrangeIcons);
        }

        private void form2ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form2 f = new Form2();
            f.MdiParent = this;
            f.Show();
        }

        private void form3ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form3 f = new Form3();
            f.MdiParent = this;
            f.Show();
        }

        private void cascadeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.Cascade);
        }

        private void horizontalToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.TileHorizontal);
        }

        private void verticalToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.TileVertical);
        }
    }
}