class WpfFormFieldTemplateEditorToolWindow : System.Windows.Window
{
    Vintasoft.Imaging.Wpf.UI.WpfImageViewer imageViewer1;
    System.Windows.Controls.Button buildFieldTemplateButton;
            
    // ...
            
    /// <summary>
    /// Form template manager.
    /// </summary>
    Vintasoft.Imaging.FormsProcessing.FormRecognition.FormTemplateManager _templateManager;
            
    /// <summary>
    /// The template editor tool.
    /// </summary>
    Vintasoft.Imaging.FormsProcessing.FormRecognition.Wpf.UI.VisualTools.WpfFormFieldTemplateEditorTool _templateEditorTool;
            
    // ...
            
    public WpfFormFieldTemplateEditorToolWindow()
    {
        // ...
            
        _templateEditorTool = 
            new Vintasoft.Imaging.FormsProcessing.FormRecognition.Wpf.UI.VisualTools.WpfFormFieldTemplateEditorTool();
        imageViewer1.VisualTool = _templateEditorTool;
            
        imageViewer1.FocusedIndexChanged += 
            new Vintasoft.Imaging.PropertyChangedEventHandler<int>(imageViewer1_FocusedIndexChanged);
            
        buildFieldTemplateButton.Click += 
            new System.Windows.RoutedEventHandler(buildFieldTemplateButton_Click);
            
        // ...
    }
            
    /// <summary>
    /// Handles the FocusedIndexChanged event of the imageViewer1
    /// to change the collection of form field templates of the visual tool.
    /// </summary>
    private void imageViewer1_FocusedIndexChanged(
        object sender,
        Vintasoft.Imaging.PropertyChangedEventArgs<int> e)
    {
        if (imageViewer1.Image == null)
        {
            _templateEditorTool.FieldTemplateCollection = null;
        }
        else
        {
            // get the form page template
            Vintasoft.Imaging.FormsProcessing.FormRecognition.FormPageTemplate pageTemplate = 
                _templateManager.GetPageTemplate(imageViewer1.Image);
            // set items of page template as current items of the visual tool
            _templateEditorTool.FieldTemplateCollection = pageTemplate.Items;
        }
    }
            
    // ...
            
    /// <summary>
    /// Handles the Click event of the buildFieldTemplateButton
    /// to create a form field template and start building of it.
    /// </summary>
    private void buildFieldTemplateButton_Click(object sender, System.Windows.RoutedEventArgs e)
    {
        // create an OMR rectangular field template
        Vintasoft.Imaging.FormsProcessing.FormRecognition.FormFieldTemplate fieldTemplate = 
            new Vintasoft.Imaging.FormsProcessing.FormRecognition.Omr.OmrRectangularFieldTemplate();
        // create a view for the field template
        Vintasoft.Imaging.FormsProcessing.FormRecognition.Wpf.UI.WpfFormFieldTemplateView fieldTemplateView = 
            Vintasoft.Imaging.FormsProcessing.FormRecognition.Wpf.UI.WpfFormFieldTemplateViewFactory.CreateView(fieldTemplate);
            
        // add field template to the collection of visual tool and
        // start building of field template
        _templateEditorTool.AddAndBuild(fieldTemplateView);
    }
            
    // ...
            
}