Update confusion

[Acorn]

Works fine in FF but doesn't close in Edge or Chrome Acorn.
I've added a 'Copy to Clipboard' button to copy the URL into another breed of browser (Source)

Cheers egg for the Copy code.

I have refined it down to a much smaller portion that I will publish back after I work out how to close the other browsers.
The code only works when launched through an XDA. Pasting the same URL into a browser acts differently and blocks the code from running:

Scripts may close only the windows that were opened by them.

Basically, a CopyClipboard icon with Link - javascript: copyUrl();
and Placeholder code of:

function copyUrl() {
  var $temp = $("<input>");
  var $url = $(location).attr('href');

  $("body").append($temp);
  $temp.val($url).select();
  document.execCommand("copy");
  $temp.remove();
}

I have removed the bang (!) from !Assistance (I am now naming it Dev Mode) so it can be visible for developing and hidden for production.
I have a Copy Clipboard & a Close icon and I dumped the code for the current URL and put them Sticky off-page to minimise overloading the page (unlike Xara with its Presentation Key pop-up!).

Acorn