public ChatPageVM(string roomName, ObservableCollection <ChatItem> chatList, ObservableCollection <User> userList, SideItem sideItem)
{
ChatList = chatList;
UserList = userList;
SideItem = sideItem;
RoomName = roomName;
(CClient.serverlist[0] as CServer).ChatPage_Return_Callback.Add(RoomName, ReturnCallback);
MessageSendCommand = new RelayParameterCommand(async(parameter) => await MessageSendAsync(parameter));
ExitCommand = new RelayCommand(async() => await ExitAsync());
}