docs-desktop/dotnet-desktop-guide/samples/snippets/csharp/wpf/introduction-to-wpf/introduction-to-wpf_34.cs

using System; // EventArgs
using System.Windows; // DependencyObject, DependencyPropertyChangedEventArgs,
                      // FrameworkPropertyMetadata, PropertyChangedCallback,
                      // RoutedPropertyChangedEventArgs
using System.Windows.Controls; // UserControl

namespace SDKSample
{
    public partial class NumericUpDown : UserControl
    {
        // NumericUpDown user control implementation
    }
}