I've investigated some more and came to the conclusion that when you make the editor visible through javascript it does start initializing, but you can't use the API functions right away. You need some sort of indicator on when initializing is done. I've also noticed that the documented CuteEditor_OnInitialized function never gets called (it should work in version 6.0 right?) so that's also no option... 

 

I'd prefer a manner to have the editor initialized also in hidden state (the same way as IE works).