That would be the proper way to handle it.
See the write up on stacking contexts (and how IE handles them differently from the other A-Grade browsers) here:
Sent: Wednesday, April 30, 2008 9:35 AM
I'm creating container in IE via JS markup, if when I call render the
HTML element I pass is nested inside a few layers of Div's I find that
any other div's that are more senior in the DOM will "come through" my
container regardless of z-index (on IE only).
My work around was to make the element passed to render a more
"senior" element in the tree. Does this make sense, are there better