Extend the sky color picker example

sky/examples/color/color-wheel.sky

Index: sky/examples/color/color-wheel.sky
diff --git a/sky/examples/color/color-wheel.sky b/sky/examples/color/color-wheel.sky
index be053749d20da63a7128ee1325faad94433fa021..f970863513c80e301368bd975d9c2035920044b3 100644
--- a/sky/examples/color/color-wheel.sky
+++ b/sky/examples/color/color-wheel.sky
@@ -7,8 +7,7 @@
 
 <sky-element name="color-wheel"
     attributes="color:string"
-    on-pointerdown="handlePointerDown"
-    on-pointermove="handlePointerMove">
+    on-pointerdown="handlePointerDown">
 <template>
   <style>
     img {
@@ -65,6 +64,7 @@ module.exports = class extends SkyElement {
   created() {
     super.created();
     this.color = "#xFF00FF";
+    this.colorChanged = function(){};
   }
   updateColor(event) {
     var bounds = event.target.getBoundingClientRect();
@@ -78,9 +78,6 @@ module.exports = class extends SkyElement {
   handlePointerDown(event) {
     this.updateColor(event);
   }
-  handlePointerMove(event) {
-    this.updateColor(event);
-  }
 }.register();
 </script>
 </sky-element>