void AddConnectionBox()
{
var uri = Dropbox.GetAuthPageAddress();
Messenger.Default.Send <NotificationMessageWithCallback>(new NotificationMessageWithCallback(uri.ToString(), new Action <string>(async(string uri1) =>
{
Dropbox.SetAccessToken(new Uri(uri1));
User = await Dropbox.GetUserInfoAsync();
RaisePropertyChanged(() => User);
})), "GetAuth");
}