cursor jump to top when typing

[meninjanho4788]

I see a error when do steps :

1. type some character 'abcdef'
2. choise Bold or Italic or Underline (of tinymce)
3. then type some character againt 'zxcvbn' ==> when you typing the cursor jump to first line

Thank you so much.
(My English is not good, sorry for the mistake)