How to upgrade Opera without losing opera-unite?

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http://askubuntu.com – Opera unite is a feature in the Opera browser that was abandoned in Opera 12. In Windows, keeping Opera 11 and installing v12 on top of it, or upgrading, opera-unite stays into the browser. In Ubuntu, by installing the v12 deb or by upgrading to v12 after adding it to software sources (like this), opera-unite is lost. Is there a way of upgrading to v12 without losing opera unite, like I was able to do in Windows? (HowTos)