private void PromotePawn_Executed(object sender, ExecutedRoutedEventArgs e)
{
var grid = e.OriginalSource as Grid;
var promotionItem = grid.DataContext as PawnPromotionItem;
var square = this.viewModel.MoveEnd;
this.viewModel.ShowOverlayState = Enums.ShowOverlayState.Hide;
this.viewModel.PromotePawn(promotionItem.FigureColor, square, promotionItem.FigureType);
this.OnPawnPromoted();
}