allow SunConstants.componentEnabledListener to be overridden by optio…

…ns in each sun component, phetsims/scenery#1112

js/NumberPicker.js

@@ -80,6 +80,9 @@ class NumberPicker extends Node {
       arrowLineWidth: 0.25,
       valueMaxWidth: null, // {number|null} - If non-null, it will cap the value's maxWidth to this value
 
+      // {function(boolean, Node, Object:options):void} - function for controlling the appearance when toggling enabled.
+      enabledAppearanceStrategy: SunConstants.componentEnabledListener,
+
       /**
        * Converts a value to a string to be displayed in a Text node. NOTE: If this function can give different strings
        * to the same value depending on external state, it is recommended to rebuild the NumberPicker when that state
@@ -376,7 +379,7 @@ class NumberPicker extends Node {
     this.mutate( options );
 
     // No need to dispose because enabledProperty is disposed in Node
-    this.enabledProperty.link( SunConstants.getComponentEnabledListener( this, { disabledOpacity: options.disabledOpacity } ) );
+    this.enabledProperty.link( enabled => options.enabledAppearanceStrategy( enabled, this, { disabledOpacity: options.disabledOpacity } ) );
 
     // Dilate based on consistent technique which brings into account transform of this node.
     const focusBounds = this.localBounds.dilated( FocusHighlightPath.getDilationCoefficient( this ) );