@jetro, it updates the Firefox user-agent string that Presto Opera uses to identify itself to a website when using Opera's "mask as" function. That string is embedded in opera.dll, and the original one is becoming stale... that is, a growing number of websites reject it for that reason, since Firefox itself is up into version 30+ already. Since Opera ASA is not updating such things in Presto Opera any longer, the only way to keep the when-needed masking alternative reasonably current is for the user to do it himself.