With the latest code and Google Chrome, do the following:

1. Right-click on a link in the admin menu and select 'open in new tab' (so the tab opens in the background, but leaves the link selected)
2. With the link still selected in the interface (and without clicking any mouse buttons), move the mouse pointer up and down across the selected link
3. Watch as the icon for that link slowly travels down the page

See https://moodle.org/mod/forum/discuss.php?d=313332 for more details.