c#

private void button1_Click(object sender, EventArgs e)
        {
            tabPage1.Show();
            tabPage2.Hide();
            tabPage3.Hide();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            tabPage1.Hide();
            tabPage2.Show();
            tabPage3.Hide();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            tabPage1.Hide();
            tabPage2.Hide();
            tabPage3.Show();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            tabControl1.Appearance = TabAppearance.FlatButtons;
            tabControl1.ItemSize = new Size(0, 1);
            tabControl1.SizeMode = TabSizeMode.Fixed;
        }