Fixed overlapping popup window

Before:
![2013-11-04 14 49 42](https://f.cloud.github.com/assets/683358/1462791/e57832a0-4509-11e3-9d7a-db43495b53da.png)

After:
![2013-11-04 14 49 21](https://f.cloud.github.com/assets/683358/1462794/f10373f0-4509-11e3-84ff-39f57d7e9a95.png)

Tested on Ubuntu 13.10 in the Google Chrome 30, Firefox 25 and Opera 12.16