Use python-wnck lib to deteterminate if workspace was changed

[vkravets]

Use libwnck library to determinate if workspace was changed. Use event behavior instead of infinity loop.

[ghost]

If you are still active, I'm going to have to say I disagree on implementing this. Replacing a infinity loop with a lib is not that much of an improvement for a lightweight program.

[vajrasky]

I am still active. Yeah, I am not so keen to use another dependency for this situation.