private void ModifyToggleButtonClick(object sender, RoutedEventArgs e)
        {
            ToggleButton currentModifyToggleButton = (ToggleButton)sender;

            if (currentModifyToggleButton != lastModifyToggleButton && lastModifyToggleButton != null)
            {
                lastModifyToggleButton.IsChecked = false;
            }

            lastModifyToggleButton = (bool)currentModifyToggleButton.IsChecked ? currentModifyToggleButton : null;

            if (lastModifyToggleButton != null)
            {
                shelfToModify           = (Shelf)ShelfsDataGrid.SelectedItem;
                AddButtonImage.Source   = new BitmapImage(new Uri(@"Assets/Icons/modify.png", UriKind.Relative));
                AddButtonTextBlock.Text = "Modyfikuj";
                AddShelfTextBox.Text    = shelfToModify.ShelfName;
            }
            else
            {
                shelfToModify           = null;
                AddButtonImage.Source   = new BitmapImage(new Uri(@"Assets/Icons/add.png", UriKind.Relative));
                AddButtonTextBlock.Text = "Dodaj";
                AddShelfTextBox.Clear();
            }
        }
        private void AddButtonClick(object sender, RoutedEventArgs e)
        {
            AddButton.IsEnabled       = false;
            AddShelfTextBox.IsEnabled = false;

            if (lastModifyToggleButton != null)
            {
                ModifyAction();
            }
            else
            {
                AddAction();
            }

            AddShelfTextBox.Clear();

            ShelfsDataGrid.DataContext = dB.GetShelfs();

            AddButton.IsEnabled       = true;
            AddShelfTextBox.IsEnabled = true;
        }