Unable to add link in advanced layout, text editor

Whenever I try to add a link in the text editor, the link pop-up window opens BEHIND the text editor window. So, I can’t get to it to add a link until I close the text editor box, and then the link can’t be created because the text editor has been closed. Please help. I won’t be able to use this theme if I can’t work with the basic functionality.

Thanks!