It works on mine mate, Links to the ticket printer are like:

`tickets.php?id={TICKETNUMBER}&a=print&notes={1|0}` etc.

Hmm.. actually, that might be triggering it, but as there is zero HTML,
it shouldn't work in the DOMDocument, and therefore should "should"
return the original code.. however, better to avoid that in future.

Added an additional filter to the URL checker to prevent it anyway.

class.AttachmentPreviewPlugin.php

@@ -948,8 +948,8 @@ public static function isTicketsView() {
         // If something has been POST'd to osTicket, assume we're not Viewing a ticket
         $tickets_view = FALSE;
       }
-      elseif (strpos($url, 'a=edit')) {
-        // URL contains a=edit, which we don't want to change yet
+      elseif (strpos($url, 'a=edit') || strpos($url, 'a=print')) {
+        // URL contains a=edit or a=print, so assume we aren't needed here!
         $tickets_view = FALSE;
       }
       elseif (strpos($url, 'index.php') !== FALSE ||