- Edited
I noticed that attachments are opened inside/over osTicket. Perhaps it's better to open them in a new window.
For this I changed the code on line 767 from ./include/class.ticket.php into:
$attachstr.= "<a class='Icon file' href='attachment.php?id=$id&ref=$hash' target='_blank'><b>$name</b></a> (<i>$size</i>) ";
Maybe there are reasons why it's opened in the same window, but in my case this works better.