title: How to set a created event's `isTrusted` property in javascript using Greasemonkey
body: <p>I would like to create and fire a KeyPress Event through a userscript in Greasemonkey but I observed that the createEvent's <code>isTrusted</code> is set to <code>false</code> all the time.</p>
  
  <p><code>isTrusted</code> is read-only property but I read that it can be set to True by extensions like Greasemonkey but it's not working for me.</p>
  
  <p>Is there a way to set <code>isTrusted</code> to <code>true</code>?.</p>