Added Cinnamon Main.isInteresting filter on windows

Please see: https://github.com/linuxmint/Cinnamon/search?utf8=%E2%9C%93&q=isInteresting

I fully recommend you verify that whatever windows have a .filter and are correctly set, on my opinion it's not currently correct in all cases.

This pull at less resolve:

![captura de pantalla de 2014-09-17 02 12 16](https://cloud.githubusercontent.com/assets/1389572/4300210/e4d1f3cc-3e41-11e4-97ad-8cb21f895bb2.png)