Public Partial Class TextSelectionWindow
    Inherits System.Windows.Window
    ' ...
    Private _imageViewer As Vintasoft.Imaging.Wpf.UI.WpfImageViewer = Nothing
    Private _textSelectionTool As Vintasoft.Imaging.Wpf.UI.VisualTools.WpfTextSelectionTool = Nothing



    Public Sub New()
        ' ...

        ' create the text selection tool
        _textSelectionTool = New Vintasoft.Imaging.Wpf.UI.VisualTools.WpfTextSelectionTool(New System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromArgb(56, 0, 0, 255)))

        ' subscribe to the text selection tool events
        AddHandler _textSelectionTool.SelectionChanged, New System.EventHandler(AddressOf _textSelectionTool_SelectionChanged)

        ' set the text selection tool as the current tool in image viewer
        _imageViewer.VisualTool = _textSelectionTool
    End Sub



    '  Handles the TextSelectionTool.Selection event.
    Private Sub _textSelectionTool_SelectionChanged(sender As Object, e As System.EventArgs)
        ' if text selection is not empty
        If _textSelectionTool.SelectedRegion IsNot Nothing AndAlso Not _textSelectionTool.SelectedRegion.IsEmpty Then
            ' show the text selection content
            System.Windows.MessageBox.Show(_textSelectionTool.SelectedRegion.TextContent)
        End If
    End Sub

End Class

public partial class TextSelectionWindow : System.Windows.Window
{
    // ...
    Vintasoft.Imaging.Wpf.UI.WpfImageViewer _imageViewer = null;
    Vintasoft.Imaging.Wpf.UI.VisualTools.WpfTextSelectionTool _textSelectionTool = null;



    public TextSelectionWindow()
    {
        // ...

        // create the text selection tool
        _textSelectionTool = new Vintasoft.Imaging.Wpf.UI.VisualTools.WpfTextSelectionTool(
            new System.Windows.Media.SolidColorBrush(System.Windows.Media.Color.FromArgb(56, 0, 0, 255)));

        // subscribe to the text selection tool events
        _textSelectionTool.SelectionChanged += new System.EventHandler(_textSelectionTool_SelectionChanged);

        // set the text selection tool as the current tool in image viewer
        _imageViewer.VisualTool = _textSelectionTool;
    }



    //  Handles the TextSelectionTool.Selection event.
    private void _textSelectionTool_SelectionChanged(object sender, System.EventArgs e)
    {
        // if text selection is not empty
        if (_textSelectionTool.SelectedRegion != null && !_textSelectionTool.SelectedRegion.IsEmpty)
            // show the text selection content
            System.Windows.MessageBox.Show(_textSelectionTool.SelectedRegion.TextContent);
    }

}