How does one detect all focus events?
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I want to have a little arrow that follows the user when he/she tabs through links etc. on my site. 

Normally you will see an outline around the link..but I have removed the outline using CSS.

In it's place I want to have a little un-obtrusive arrow that I prefer.

I don't want to add an event listener to each element ( there are many ) as I think there must be an easier way.

I'm guessing there has to be a point in the DOM where I can capture all `events` of type `focus` and from that grab the element using `this` and from there determine the location of the event and then move the tiny arrow there.