private void BtnToevoegen_Click(object sender, EventArgs e)
{
UserDialog dia = new UserDialog(true);
dia.ShowDialog();
List <User> beheerUser = _gc.BeheerUser();
listBox1.DataSource = beheerUser;
}
private void BtnWijzigen_Click(object sender, EventArgs e)
{
User updateUser = (User)listBox1.SelectedItem;
UserDialog dia = new UserDialog(false, updateUser);
dia.ShowDialog();
List <User> beheerUser = _gc.BeheerUser();
listBox1.DataSource = beheerUser;
}