private void _connectButton_Click(object sender, EventArgs e)
{
Chatroom room = (Chatroom)_roomListBox.SelectedItem;
JObject changeRoomPacket = new JObject(
new JProperty("CMD", "joinRoom"),
new JProperty("Room", room.Name));
var json = changeRoomPacket.ToString();
byte[] data = Packet.CreateByteData(json);
client.Send(data);
room.AddUser(user);
ChatRoomGUI chatGUI = new ChatRoomGUI(client, room, user);
chatGUI.Text = room.Name;
chatGUI.ShowDialog();
}