[CODE lang="csharp" title="Form1"]public partial class Form1 : Form
    {
        private AltForm ikinciForm;
        public Form1()
        {
            InitializeComponent();
        }
        private void buttonShowHide_Click(object sender, EventArgs e)
        {
            if(!AltForm.isExist)
            {
                ikinciForm = new AltForm();
            }
            if(!ikinciForm.isOn)
            {
                ikinciForm.Show();
                ikinciForm.isOn = true;
            }
            else
            {
                ikinciForm.Hide();
                ikinciForm.isOn = false;
            }
            this.buttonShowHide.Text = ikinciForm.isOn ? "Gizle" : "Göster";
        }
    }[/CODE]
[CODE lang="csharp" title="AltForm"]public partial class AltForm : Form
    {
        public static bool isExist = false;
        public bool isOn = false;
        public AltForm()
        {
            InitializeComponent();
            this.Hide();
        }
        private void AltForm_Load(object sender, EventArgs e)
        {
            isExist = true;
        }
        private void AltForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            isExist = false;
        }
    }[/CODE]
Form1 içerisinde tek bir buton var sadece.
Bu örneği iyice inceleyin.