how to Create username hover dropdown menu

use Flex Level Drop Down Menu at dynemicDrivie Site:
 
The link is
 
http://www.dynamicdrive.com/dynamicindex1/flexdropdown.htm[^]

Please provide some ideas on how to implement this
There can be multiple ways to do it. AFAIK, here at CP, it's CSS driven. Define a hover style for the username. In the style, set display property of the dropdown div element as to display.
 
Underlying logic is to have a div that is hidden by default. based on some event, you need to show this div. Here, hover is that event that is being used. If you don't want CSS way, you can define onmouseover event for username and then in JavScript, show the needed div. On mouseout, hide it back.
 
Examples, you yourself posted couple of them in question! Now, try out and post specific issues if you face any.