During writing a HTML Formatted message, I cannot insert a TAB (\t) from the keyboard, because it moves the focus from the message textarea to the font selector area. It is not convenient, because during writing a Plain Text message, it inserts a TAB (\t) character as expected. Even worse, if you don't pay attention and keep typing, you'll end up your text messed up with formatting.
I suggest to modify this behavior, e.g. make it possible, to chose what the tab key should do.