when the slider of the LuminancePad is at its minimum or maximum the control visualized wrong color.
TextBlocks RGB CMYK HSL are cut when the style is extracted from blend. As a workaround use an implicit style approach. You can have folder with your XAML files and edit the Style of RadColorEditor in them. http://docs.telerik.com/devtools/wpf/styling-and-appearance/styling-apperance-implicit-styles-overview