Hand-off control to the ColorView after template is applied in ColorPicker

This solution doesn't require the hacky IsHostedInColorPicker property

src/Avalonia.Controls.ColorPicker/ColorPicker/ColorPicker.cs

@@ -1,4 +1,6 @@
-namespace Avalonia.Controls
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Controls
 {
     /// <summary>
     /// Presents a color for user editing using a spectrum, palette and component sliders within a drop down.
@@ -11,8 +13,33 @@
         /// </summary>
         public ColorPicker() : base()
         {
-            // Completely ignore property changes here
+        }
-            // The ColorView in the control template is responsible to manage this
+
+        /// <inheritdoc/>
+        protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+        {
+            base.OnApplyTemplate(e);
+
+            // Until this point the ColorPicker itself is responsible to process property updates.
+            // This, for example, syncs Color with HsvColor and updates primitive controls.
+            //
+            // However, when the template is created, hand-off this change processing to the
+            // ColorView within the control template itself. Remember ColorPicker derives from
+            // ColorView so we don't want two instances of the same logic fighting each other.
+            // It is best to hand-off to the ColorView in the control template because that is the
+            // primary point of user-interaction for the overall control. It also simplifies binding.
+            //
+            // Keep in mind this hand-off is not possible until the template controls are created
+            // which is done after the ColorPicker is instantiated. The ColorPicker must still
+            // process updates before the template is applied to ensure all property changes in
+            // XAML or object initializers are handled correctly. Otherwise, there can be bugs
+            // such as setting the Color property doesn't work because the HsvColor is never updated
+            // and then the Color value is lost once the template loads (and the template ColorView
+            // takes over).
+            //
+            // In order to complete this hand-off, completely ignore property changes here in the
+            // ColorPicker. This means the ColorView in the control template is now responsible to
+            // process property changes and handle primary calculations.
             base.ignorePropertyChanged = true;
         }
     }