public override void OnApplyTemplate() { base.OnApplyTemplate(); PART_PictureBox = this.EnsureTemplateChild <System.Windows.Forms.PictureBox>("PART_PictureBox"); PART_PictureBox.LoadProgressChanged += pictureBoxLoading_LoadProgressChanged; PART_PictureBox.LoadAsync(UriSource.OriginalString); PART_PictureBox.LoadCompleted += PART_PictureBox_LoadCompleted; }