Open two web pages in tabs:

*) One page that refreshes itself, maybe once a minute
*) One page where you need to fill out a form, like a web mail site

Start typing in the form. When the other page refreshes itself, the form loses
focus and nothing more is entered into the form until you click on it. When you
have several tabs with refreshing pages, possibly at different intervals, this
becomes very annoying. I am no typist, I look at my fingers while I write, so I
constantly have to retype some text each time focus is lost.