How do I get the actual object created by FrameworkElementFactory?

Question

I am using the following code to create a draggable control by adding a template control to the Thumb. However I need to call methods on the FilePickerPopup object that gets created in order to set delegates etc. How can I access the object that gets created ? The method shown below fails to get the actual object.

Is there a simpler method to create a draggable UserControl than this ? As I understand it this may be a deprecated method anyway. Thanks.

filePicker = new Thumb();

ControlTemplate template = new ControlTemplate();

var filePickerControl = new FrameworkElementFactory(typeof(Controls.Popups.FilePickerPopup));

filePickerControl.Name = "FilePickerControl";

template.VisualTree = filePickerControl;

filePicker.Template = template;

FilePickerPopup fpp = filePicker.Template.FindName("FilePickerControl", filePicker) as FilePickerPopup;

fpp.SetParent(parent);

Note that the FilePickerPopup has a public method SetParent(object parent);