1. I installed your application, followed your instruction and it works for me.

 

2. If you click the preview window and click the normal window, are you able to edit?

 

If so, it's a height issue.

 

I suggest you try different doctype then test again.

 

Maybe some code in example JavaScript don't work well in different doctype.

 

3. Another option to debug this issue is removing the JavaScript code one by one. If it works, then add the script back one by one untill you find out which script causes the problem.

 

4. If you still think the problem is caused by Cute Editor,  here are some example showing how editor works in Ajax.