Appearing div attached to header row shows up behind Infinite Scrolling grid

btBill

I have a table that has infinite scrolling on it.
The header row has jquery.mouseenter events on the cells that show a div with some predefined sorting and filtering choices.
The sorting and filtering work fine, but when the div appears, it ends up behind the table.

I've tried adding a z-index of up to 10000 on the div, but no use. I see a little part of it in the header row, but then the rest is hidden behind the scrolling table.

Any suggestions on how I can get this to appear correct above the table rows?

Thanks./