此程序在于测试tabcontrol控件的使用方法。主要是通过选项卡控件分别激活对应的子窗体。
窗体如图所示：
1个Tabcontrol控件，两个子窗体。
 
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace tabcontrolTest2
{
    /// <summary>
    /// Form1 的摘要说明。
    /// </summary>
    public class Form1 : System.Windows.Forms.Form
    {
        childForm1 mychildForm1=new childForm1();
        childForm2 mychildForm2=new childForm2();
        private System.Windows.Forms.TabControl tabControl1;
        private System.Windows.Forms.TabPage tabPage1;
        private System.Windows.Forms.TabPage tabPage2;


        /// <summary>
        /// 必需的设计器变量。
        /// </summary>
        private System.ComponentModel.Container components = null;

        public Form1()
        {
            //
            // Windows 窗体设计器支持所必需的
            //
            InitializeComponent();

            //
            // TODO: 在 InitializeComponent 调用后添加任何构造函数代码
            //
        }

        /// <summary>
        /// 清理所有正在使用的资源。
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null) 
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows 窗体设计器生成的代码
        /// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            this.tabControl1 = new System.Windows.Forms.TabControl();
            this.tabPage1 = new System.Windows.Forms.TabPage();
            this.tabPage2 = new System.Windows.Forms.TabPage();
            this.tabControl1.SuspendLayout();
            this.SuspendLayout();
            // 
            // tabControl1
            // 
            this.tabControl1.Controls.Add(this.tabPage1);
            this.tabControl1.Controls.Add(this.tabPage2);
            this.tabControl1.Dock = System.Windows.Forms.DockStyle.Top;
            this.tabControl1.Location = new System.Drawing.Point(0, 0);
            this.tabControl1.Name = "tabControl1";
            this.tabControl1.SelectedIndex = 0;
            this.tabControl1.Size = new System.Drawing.Size(632, 32);
            this.tabControl1.TabIndex = 1;
            this.tabControl1.SelectedIndexChanged += new System.EventHandler(this.tabControl1_SelectedIndexChanged); //必须手工添加此代码
            // 
            // tabPage1
            // 
            this.tabPage1.Location = new System.Drawing.Point(4, 21);
            this.tabPage1.Name = "tabPage1";
            this.tabPage1.Size = new System.Drawing.Size(624, 7);
            this.tabPage1.TabIndex = 0;
            this.tabPage1.Text = "tabPage1";
            // 
            // tabPage2
            // 
            this.tabPage2.Location = new System.Drawing.Point(4, 21);
            this.tabPage2.Name = "tabPage2";
            this.tabPage2.Size = new System.Drawing.Size(544, 79);
            this.tabPage2.TabIndex = 1;
            this.tabPage2.Text = "tabPage2";
            // 
            // Form1
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
            this.ClientSize = new System.Drawing.Size(632, 273);
            this.Controls.Add(this.tabControl1);
            this.IsMdiContainer = true;
            this.Name = "Form1";
            this.Text = "Form1";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.tabControl1.ResumeLayout(false);
            this.ResumeLayout(false);

        }
        #endregion

        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main() 
        {
            Application.Run(new Form1());
        }


        private void opchild()
        {
            mychildForm1.MdiParent = this;
            mychildForm2.MdiParent = this;
            mychildForm1.Show();
            mychildForm2.Show();
        }


        private void tabControl1_SelectedIndexChanged(object sender, System.EventArgs e)
        {    switch(this.tabControl1.SelectedIndex)    
            {   case 0:
                mychildForm1.Select();;
                break;      
                case 1:      
                mychildForm2.Select();; 
                break;   
            } 
        }

        private void Form1_Load(object sender, System.EventArgs e)
        {
           opchild();
        }
    }
}