Aloha Editor as well as Opera did improve since Aug 2010. At that time Aloha Editor v0.9.3 and Opera 10 did not work properly together. I did some debugging and improvements with Maike Tylor from Opera. The current dev version of Aloha Editor has the bad alert replaced with a console.log and Opera 11 offers better support for contentEditable. Due to the huge refactoring and at the same time major improvements and extensions the dev is not yet stable enough to be released. We expect a release within a month.