The reason is this line:
inc\media.php(453): 'onclick="return confirm(\''.$ask.'\')" onkeypress="return confirm(\''.$ask.'\')">'.
According to the (sometimes erroneous) accessibility guidelines of the W3C (http://www.w3.org/TR/WCAG10-HTML-TECHS/#directly-accessible-scripts) onclick-events should always go with a onkeypress-event. But as this proved to be problematic (as can be seen here for example:
http://www.rnib.org.uk/wacblog/articles/too-much-accessibility/too-much-accessibility-–-multiple-javascript-event-handlers/) and is not needed in most browsers (except for Mac IE, and we can ignore it, can't we?).
And this is not the only occurrence of onkeypress ...