protected void Close(bool?result)
        {
            if (IsClosed)
            {
                throw  new InvalidOperationException("Already closed");
            }

            OnClosed();

            IsClosed = true;

            ChildViewModelManager.Close(this, result);
        }
 public Task <bool?> ShowDialog()
 {
     return(ChildViewModelManager.ShowDialog(this));
 }
 public Task Show()
 {
     return(ChildViewModelManager.Show(this));
 }