ColorCanvas: fixed bug when selecting black or white the color spectrum slider would jump to red.

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/ColorCanvas/Implementation/ColorCanvas.cs

@@ -324,6 +324,8 @@ namespace Microsoft.Windows.Controls
             _currentColorPosition = null;
 
             HsvColor hsv = ColorUtilities.ConvertRgbToHsv(color.R, color.G, color.B);
+
+            if (color.R != color.G && color.R != color.B)
                 _spectrumSlider.Value = hsv.H;
 
             Point p = new Point(hsv.S, 1 - hsv.V);