After installing debian sid and gnome shell on that, And after that I found the gnome shell a cool thing, I wrote a proxy switcher in command line for myself because the original gnome-control-center proxy switcher is really useless and my usual browser - Google Chrome - is not perfect enough to have an internal proxy settings.

Now after getting familiar with gnome shell development system, I built a gnome shell extension to give me ability of switching proxy settings by some clicks, I wrote an install script for my extension+proxyswitcher and now It's available to download.