private void LbClients_DoubleClick(object sender, EventArgs e)
        {
            if (lbClients.SelectedItem == null)
            {
                return;
            }

            string userNickname = lbClients.SelectedItem.ToString();
            User   user         = users.Find(u => u.Nickname.Equals(userNickname));

            clientForm frm = new clientForm(user);

            frm.OnSendButtonPressed += OnSendButtonPressedHandler;
            frm.OnClientFormClosing += OnClientFormClosingHandler;

            frm.Show();

            remoteScreens.Add(frm);
        }
 void OnClientFormClosingHandler(clientForm frm)
 {
     remoteScreens.Remove(frm);
 }