sortable bug in 1.6rc2 when using floating items?

sortable bug in 1.6rc2 when using floating items?


I think there is a bug in the sortable module in 1.6rc2 as it works
with 1.5.2.
I screencasted the problem with Jing, so you have a better idea what I
mean:
Problem (casted in IE7/Parallels):
http://screencast.com/t/ZIcVOoGWxJR
No Problem (at least not that - there's still some glitches but
nothing that's hard to correct).
http://screencast.com/t/U4gINcewNe
I use a simple
    $("#boxes").sortable({
     placeholder: "ui-selected",
        forcePlaceholderSize: true,
        revert: false
    });
Any updates on this issue?
Tried everything without success for hours.
Best, Sebastian