Better to just add a new stop button rather than overload minimization. In any case, if your concern is web pages, your browser needs to implement this, not your window manager (unless you are not using tabbed browsing, which I doubt).
Do you happen to know why web browsers don't already do something like this? I find that a large number of domains are called every minute. I say domains as most of them seem to be providing Javascript, although some of them are the web site I have loaded. Very occasionally I can see a legitimate purpose, such as refreshing a page showing a web interface to an email account, but most of the time there doesn't seem to be a legitimate purpose.
Btw, this is from using Little Snitch on the Mac. If I temporarily block the refresh, nothing bad ever seems to happen.
Actually, I avoid using tabs. Reason being that I often have way too many pages displayed and have then difficulties finding a give one (chrome's taskmanager comes to the rescue, but that's not the most convenient workflow). The 'window list' applet of the DE allows me to find windows, but not tabs.
