There's a submitted bug report #4711 that describes a condition where tinyMCE loses track of wrapping when in full screen mode. I found the same issue when I upgraded to 3.5.2. 

It's fairly easy to reproduce. Start tinyMCE in full screen mode (I use the latest Firefox), start typing until the text starts to wrap around, resize the browser, and then the text no longer wraps, but is a single line that extends beyond the browser window.

I've tried adding the autoresize plugin, but this didn't resolve this. I've also tried re-establishing full screen mode, but this didn't resolve it either.

I'm wondering if someone could suggest a method for working around this issue. I'd like not to go back to an older version if I don't have to. In my application, the user/editor is always placed in full screen mode by default.

Thank you.
Carlos S. Zamudio