No transparency for Windows 8 Metro

So I recently bought WindowBlinds in the hope that I would be finally able to get transparency back into Windows 8, just like in Vista and 7, but I can't find the option to do so. It's supposed to be in the "color" tab which isn't there:



The other themes have the color tab so I can use transparency but I want to have transparency with the default Metro theme. How do I fix this?