private void btnAdd_Click(object sender, EventArgs e)
    {
        ControlsDisabled();                       // It's enough to disable here
        contactForm = new FormContact();

        if (contactForm.ShowDialog() == DialogResult.OK)
        {
            contact = contactForm.contact; // You need only the Contact object
            contacts.Add(contact);         // You add the contact to to bound list
            txtFname.Text = contact.FirstName;
            txtLname.Text = contact.LastName;
        }
        ControlsEnabled();                        // Enable even if dialog fails
    }
    private void btnEdit_Click(object sender, EventArgs e)
    {
        ControlsDisabled();
        contact     = lstBoxAdd.SelectedItem as Contact; // Retrieve selected Contact
        contactForm = new ContactForm(contact);          // Pass it to the contactForm

        if (contactForm.ShowDialog() == DialogResult.OK)
        {
            contact       = contactForm.contact;
            txtFname.Text = contact.FirstName;
            txtLname.Text = contact.LastName;
            //lstBoxAdd.Items.Add(contact.firstname + " " + contact.lastName); --> Not needed
        }
        ControlsEnabled();
    }