Which <ul>, the one with the sub items? You don't need too. Say you have 20000px bottom margin on <a class="target"> or whatever it is. This pushes the menu out of site (until you scroll that is ). Then, on hover, you make the margin 0. Pow, it's now visible as it's brought back up beneath the <a>. Though I haven't figured out how you'd hide it... like I said, quick theory
why don't you pull it up? then it will not trigger any scrollbar.

I sent an email to Stu Nicholls about this topic. Hopefully he'll chime in with some ideas too
i hope he doesn't steal it and say its his invention... i worked too much on it to have him take all the credit.

I guess I've always ruled out stuff like that since it's likely to mess up other code on the page.
the dropdown does not break content on any page, its like an average dropdown and has no effect on the content around it.
although feel free to send any working version.