Issue with nested sortable and Internet Explorer

Issue with nested sortable and Internet Explorer

Hi,
I have in my application a SQL query builder (as seen in screenshot
query.png). Basically my screenshot shows a query like:
(attr1 like foo% AND attr2!=bar) OR (attr1 like moo% AND attr2=bar...
With this query builder you can add as many attributes as you want
(attributes are the dark green blocks) and group them together with
logical OR/AND parenthesis (the light green blocks). Each attribute
can be edited/deleted and the whole structure can be reorganized. For
instance, I can move an attribute from one group of parenthesis to
another. I can also move a group inside another group. To accomplish
this I used ui.sortable widget. This works great in Firefox 2/3, Safari
and Chrome but not in Internet Explorer 6/7/8.
The issue with Internet Explorer is when I move an attribute from a
group to another one, the sortable widget create 2 placeholders and
when I drop my attribute it gets not properly positioned (see screenshot
ie-bug.png).
I put together that sample so you can see the bug (attached
sortable-ie-bug.zip). Please unzip in a folder and open nested.html in
IE to reproduce the bug.
I am not sure if this an issue with my code or if this is a bug with
sortable. It looks like the hover events bubble up from #subgroup* to
#maingroup (see code example in zip file) and the widget shows a
placeholder in both places.
Any ideas?
Thank you!
j.