Cannot paste into Google Docs when copying from external source

I've created a fogger application for Google Drive (url: https://drive.google.com/) with no other modifications. The problem is that whenever I copy text from my browser, a text editor or another program I cannot paste it into a Google Document.

To reproduce:
1. Open a Google text document from the application
2. Copy a text from my browser (Mozilla Firefox or whatever)
3. Try to paste it into the text document by pressing Ctrl+V. Nothing happens - allthough pressing it several times sometimes works.

Copying and paste text from inside the fogger application itself works fine and other fogger applications like Google Plus works fine when copying text from other programs.

I use Ubuntu 12.04 with Unity. Please let me now if you'll need any other information.