The first example shows how to change the window's status if used in any tag but an anchor tag:

If used with an anchor tag and onMouseOver, you have to conclude the JavaScript program with a return true;. Never mind what it means, what it does is, it tells the event handler that it can forget about the MouseOver event. If we didn't tell the browser that it would go on to tell the A tag that it had a MouseOver event, and the A tag would bring up the URL of the link, overwriting the funny message we put there.
 
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