I notice that when you switch to the Preview tab and then type on the keyboard, the text is added to the code editor, which of course mucks up your code. This is especially noticable if the page has no forms, but even if the page has a form I have been able to somehow move away from the form and the characters I type, thinking they are going to form input box, actually go to the code editor.
Shouldn't the input be directed to the preview window, not the code editor?