Annoying Opacify Feature in 10.10

Okay. I found this so-called opacify feature extremely annoying (I’ll just call it retarded to show my anger towards it). Basically, it makes any other overlapping windows to fade out from the window currently moused over with. It doesn’t sound so annoying but you will know if you use it for an hour or two. I stood up with this annoyance for almost a month because I got busy with other stuffs. I finally determine to spend some time to fix it and it wasted me like a couple hours. Anyway, just follow this link for solution.