[thelist] CSS-Reliant Dropdown Menu's - What are the downsides?

[Jon Hughes]

I recall seeing a discussion (though I don't think it was on thelist) 
regarding why CSS menu's are bad for usability.

The two reasons that I recall are:

1) Initiates onmouseover (:hover) and not onmousedown
2) List 'closes' when you go even 1px off, whereas native dropdowns use 
a delay to combat that.

Can anyone think of anything else that is wrong with using CSS 
dropdowns, as apposed to (form-based dropdowns (<select><option>))

Thanks,

 - Jon Hughes
Phazm.com/notes