Doing the `this.screen.classList.contains('utility-tray')` check is unnecessary, `elem.classList.add()` won't add a duplicate if the class already exists. So instead of always doing the check and sometimes doing the add, reduce it to always do the add.

```js
var div = document.createElement("div");
// bootstrap some classes
div.className = "foo bar baz";

console.log( div.classList );
// > [ "foo", "bar", "baz ]

// Add "foo", even though it already exists:
div.classList.add("foo");

// Observe no duplication
console.log( div.classList );
// > [ "foo", "bar", "baz ]

```