I found that the module has problem when using on IE 9.
Steps to reproduce:
1. open the "Admin" drawer by clicking on the spanner icon.
2. At this time the "cross" icon still work. The cross can close the admin drawer.
3. Click any of the items on the admin drawer to open an administrative page on overlay.
4. Part of the newly opened page will be covered by the admin drawer (as shown in the attached image). Now the "cross" icon stops function. Only a refresh (F5) can get it back to work.