 <p>You can't set the <code>window.screen</code> values in the <code>LoadStarted</code> event, but you can in the <code>Intialized</code> event. So, instead, the code would look like this:</p> <pre><code>tab.onInitialized = function () { tab.evaluate(function () { window.screen = { width: 1920, height: 1080 }; }); }; </code></pre>