jquery UI dialog and date picker

If you place a jquery UI date picker control (triggered by on focus on
an input field, just the classic example) on a jquery UI dialog, the
date picker will appear under the dialog. Can anyone suggest a quick fix
to that ? I'm not some CSS guru and I'd imagine I should somehow set the
zIndex to be bigger than ui dialog's zindex but I am not sure how to do that
Thanks,
Dorel