IE6 and the infamous "tooltip"

Hi !
I know this will be around the 765th posts about this topic, but still, it's not answered so....
I have used a sample code on another forum which works fine to display tooltip in IE6. But my problem is that it's not working when placed in a <select><option> tag...  I know it's more of an HTML question, but everything is generated by server code (rendered) since I'm working on a control, maybe someone here could help me.
Another thing is that the tooltip seems to be hidden behind the list control.

Here is the page code. This is just for test purpose to show that it works in some condition but not with listbox :
<!DOCTYPE html PUBLIC "-//W3C//DTD Xhtml 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" co ...