private void listView1_DoubleClick(object sender, EventArgs e)
{
string indexUser = listView1.SelectedItems[0].Text;
User utilizadorAlterar = context.UserSet.Where(i => i.Username == indexUser).FirstOrDefault();
ProjectoESGPS.Properties.Settings.Default.UserAlterar = utilizadorAlterar.Username;
ProjectoESGPS.Properties.Settings.Default.Save();
AddUser addUser = new AddUser();
addUser.Show();
this.Hide();
}