Transparent Message Window

I am working with Writer. I’m doing something with a doc file document. I have a problem. Everytime I type something will appear a transparent message window. It’s gone if I press space key. Can somebody tell me what’s happening. And how to stop it. It hapens again and again.

Libreoffice 4.4, Ubuntu 14.04

What are your language settings in Ubuntu and LibO and input methods in Ubuntu?

The language settings are English.

What is the content of the transparent message window?

There’s nothing written there. Unfortunately, my point doesn’t allow me to post the image. But if you want to, you may get the image here Dropbox - Screenshot from 2015-03-26 20:40:00.png - Simplify your life. If you see the picture, it’s colour orange, it’s because of the screenshot. Actually, it’s transparent. I can see my document behind the window.