public async Task<bool> KeypadToNUD(NumericUpDown sender,  Window owner)
{
  sender.Background = Brushes.Red;
  sender.Value = Math.Round((decimal)sender.Value, (int)sender.Increment);

  var form = new NumericView((double)sender.Minimum, (double)sender.Maximum, (double)sender.Value);
  var result =  await form.ShowDialog<DialogResult>(owner);
  if (result == DialogResult.OK)
  {
    sender.Value = (decimal)form.ReturnValue;
    sender.Background = Brushes.AliceBlue;
    return true;
  }
  else if (result == DialogResult.Cancel)
  {
    sender.Background = Brushes.AliceBlue;
  }
  return false;
}


 if (await mf.KeypadToNUD((NumericUpDown)sender, this))