public LibrarianMenuViewModel(NavigationViewModel nvm)
 {
     _navigationViewModel = nvm;
     LogOutCommand        = new BaseCommand(LogOut);
 }
 public LoginViewModel(NavigationViewModel nvm)
 {
     _navigationViewModel = nvm;
     SubmitCommand        = new RelayCommand(Submit);
 }
 public StartMenuViewModel(NavigationViewModel nvm)
 {
     _navigationViewModel = nvm;
     LoginCommand         = new BaseCommand(OpenLogin);
     RegisterCommand      = new BaseCommand(OpenRegister);
 }