private void BookmarkButton_Click(object sender, MouseButtonEventArgs e)
{
addbook = new AddBookmark(Title, WebView.Address, mainWindow);
addbook.HorizontalAlignment = HorizontalAlignment.Right;
addbook.VerticalAlignment = VerticalAlignment.Top;
addbook.Margin = new Thickness(0, -20, 30, 0);
addbook.Width = 300;
addbook.Height = 100;
addbook.Visibility = Visibility.Visible;
container.Children.Add(addbook);
}