There will always be a way to hide &#x2F; obfuscate the action, making it seem to the browser that it was user-initiated.<p>I guess Mozilla have weighed up the convenience&#x2F;security balance of browser control of the clipboard, and have put in a minimal protection scheme to make it clear that code <i>should not</i> play with it behind the user&#x27;s back, but Mozilla knows that they can&#x27;t really stop it.