AddonSDK MouseOver Effect for Toolbar Buttons

addonsdk.mouseover.js

const { browserWindows } = require("sdk/windows");
const { CustomizableUI } = require('resource:///modules/CustomizableUI.jsm');
const { viewFor } = require("sdk/view/core");
const { ActionButton } = require("sdk/ui/button/action");

var myButton = ActionButton({
	id: "myButton",
	label: "My Button",
	icon: { "16": "./icon-16.png", "32":"./icon-32.png", "64": "./icon-64.png" },
	onClick: function(state) {
		console.log("My Button was clicked");
	}  
});

//create a mouseover effect for a control
exports.MouseOver = (whatbutton, whatwindow, whatfunction) =>{
	CustomizableUI.getWidget( viewFor(whatbutton).id ).forWindow(whatwindow).node.addEventListener('mouseover', whatfunction, true);
};

function myMouseOverFunction(){
  console.log("mousing over...");
}


//add events to the browser window
for(let w of browserWindows){
	exports.MouseOver(myButton, viewFor(w), myMouseOverFunction);		//add mouseover event to spatToggleButton
}