Till-
Yes. But do you know what actually will happen? You edit a long text with some of this browsers, click on the tag-icon, nothing happens (seemingly), you continue editing, and in the end, at the end of the text some silly tags are inserted ...
1) They're not silly. 2) This only affects about 5% of users. 3) It only affects large pages and only happens when the cursor isn't within visible range of the end. 4) You make a prediction that users will not notice what has happened. This prediction can only be properly tested through actual use.
It's trivial to disable the toolbar in non-Moz/IE. The code for doing that is already there. I just don't intend to do it unless it's absolutely necessary.
Regards,
Erik