A design error in Opera 8.01 and earlier allows user-assisted attackers to execute arbitrary code by overlaying a malicious new window above a file download dialog box, then tricking the user into double-clicking on the "Run" button, aka "link hijacking".
https://euvd.enisa.europa.eu/vulnerability/EUVD-2005-2408
http://www.vupen.com/english/advisories/2005/1251
http://www.securityfocus.com/bid/15835
http://www.opera.com/linux/changelogs/802/
http://securitytracker.com/id?1015353