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 WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Label label = new Label();
            Form form = new Form();
            form.Controls.Add(label);
            form.Show();
            form.TopLevel = false;
            form.FormBorderStyle = FormBorderStyle.None;

            TabPage tab = new TabPage();
            tab.Controls.Add(form);
            tabControl1.TabPages.Add(tab);
            form.Dock = DockStyle.Fill;
            label.Text = "" + tabControl1.TabPages.Count;
        }
    }
}