I wonder if there are benign use-cases for simulating mouse clicks using event.initMouseEvent. I found that it is used for creating pop-under ads in the following way:

        var e = document.createEvent('MouseEvents');
        e.initMouseEvent('click', true, true, window, 0, 0, 0, 0, 0, true, false, false, true, 0, null);
        a.dispatchEvent(e);

This code simulates a click on the opening browser window, to force the newly opened window beneath it. Evil.

I'm thinking of simply preventing all simulated clicks in my own browser via a browser extension, but I wonder if I might break useful websites and behavior in the process. Therefore I wonder what situations justify simulating mouse clicks, and if there are big sites that use it in non-evil ways.