public override void OnApplyTemplate() { base.OnApplyTemplate(); _spectrumRectangle = GetTemplateChild("PART_SpectrumDisplay") as Rectangle; _colorThumb = GetTemplateChild("Thumb") as ColorThumb; if (_colorThumb != null) { _colorThumb.PreviewMouseLeftButtonUp += _colorThumb_MouseLeftButtonUp; } UpdateColorSpectrum(); OnValueChanged(Double.NaN, Value); }