[OU] How to anonymize Opera?

[macintoshzoom]

How to anonymize Opera?

The https://www.jondos.de/en/anontest test site from JONDO (formerly
Jap) anonymizer network warns me about lot of issues on my opera, the
worst one is that it informs about the browser and my OS (even when
using the opera built-in useragent tweaker, set to firefox or explorer).
This useragent tweaker don't works for https.

Some one told in this mailist that I should reverse engineer opera
(hexdump editor? to tweak something, but i lost my mailbox recently.

Any help welcome!

Mac.