How can you change the highlighted text color for a WPF TextBox?

Question

The WPF TextBox natively makes use of the System Highlight color for painting the background of selected text. I would like to override this and make it consis

Answer 1

This is a Windows 8.1 .Net 4.6.1 tested solution to customize the SelectionBrush of each TextBox in the app:

/// Constructor in App.xaml.cs
public App() : base()
{
    // Register an additional SelectionChanged handler for appwide each TextBox
    EventManager.RegisterClassHandler(typeof(TextBox), TextBox.SelectionChangedEvent, RoutedEventHandler(_textBox_selectionChanged));
}

private void _textBox_selectionChanged(object sender, RoutedEventArgs e)
{
    // Customize background color of selected text
    (sender as TextBox).SelectionBrush = Brushes.MediumOrchid;

    // Customize opacity of background color
    (sender as TextBox).SelectionOpacity = 0.5;
}

If you want to include RichTextBox replace type name TextBox 4 times by TextBoxBase.