内容:
child.cs
------------------------------------------------------------

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;

namespace testagain
{
    /// <summary>
    /// Summary description for child.
    /// </summary>
    public class child : System.Windows.Forms.Form
    {
        private System.Windows.Forms.Label lbl_about;
        private System.Windows.Forms.Label label1;
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components 
= null;

        public child(Form f_MainForm)
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();
            this.MdiParent = f_MainForm;

            //
            // TODO: Add any constructor code after 
InitializeComponent call
            //
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if(components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not 
modify
        /// the contents of this method with the code 
editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.lbl_about = new System.Windows.Forms.Label
();
            this.label1 = new System.Windows.Forms.Label();
            this.SuspendLayout();
            // 
            // lbl_about
            // 
            this.lbl_about.Font = new System.Drawing.Font
("黑体", 24F, System.Drawing.FontStyle.Regular, 
System.Drawing.GraphicsUnit.Point, ((System.Byte)(134)));
            this.lbl_about.Location = new 
System.Drawing.Point(56, 48);
            this.lbl_about.Name = "lbl_about";
            this.lbl_about.Size = new System.Drawing.Size
(344, 40);
            this.lbl_about.TabIndex = 0;
            this.lbl_about.Text = "MDI窗体操作演示示例";
            // 
            // label1
            // 
            this.label1.Location = new System.Drawing.Point
(312, 112);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(136, 
16);
            this.label1.TabIndex = 1;
            this.label1.Text = "东方蜘蛛     2001-7-1";
            // 
            // child
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size
(6, 14);
            this.ClientSize = new System.Drawing.Size(536, 
329);
            this.Controls.AddRange(new 
System.Windows.Forms.Control[] {
                                                            
              this.label1,
                                                            
              this.lbl_about});
            this.Name = "child";
            this.StartPosition = 
System.Windows.Forms.FormStartPosition.CenterParent;
            this.Text = "MDI窗体操作演示_子窗体";
            this.WindowState = 
System.Windows.Forms.FormWindowState.Maximized;
            this.ResumeLayout(false);

        }
        #endregion
    }
}