private void registerToolStripMenuItem_Click_1(object sender, EventArgs e)
 {
     RegistrationForm form = new RegistrationForm();
     form.ShowDialog();
 }
 private void registerToolStripMenuItem_Click(object sender, EventArgs e)
 {
     using (RegistrationForm registrationForm = new RegistrationForm())
     {
         registrationForm.ShowDialog(this);
     }
 }