I have something solid here. When I put something draggable into something resizable, the bug occurs. In every browser.
BUT it is fixed in one version of jQuery.ui (not the future RC3 !)
I tried first with the automatic RC2 build (from the http://ui.jquery.com/download_builder/) and as you can see here : http://www.dubuscyril.com/jquerybug/jQueryRC2.html the bug occurs.
But to make things clean, I wanted to use the links provided in the example of jQuery.ui documentation, so I made a page with the links like http://code.jquery.com/jquery-latest.js etc ...
And this time, there was no bug !
So I tried to look at the repository, and I found two differents repositories. One at code.google.com. With links like : http://jquery-ui.googlecode.com/svn/tags/latest/ui/ui.core.js
With this version, no problem, it works : http://www.dubuscyril.com/jquerybug/jQueryLatest.html
BUT I found another repository for jQuery.ui, the one linked to this bugtracker : http://ui.jquery.com/bugs/browser and it seems up to date
I tried sources from this (copy and paste directly from the browser, i'm a bit lazy), and the bug occurs ! As shown here : http://www.dubuscyril.com/jquerybug/jQueryTrunk.html
I think the version from the repository linked to this bugtracker is the future release candidate 3, and with this version the bug occurs, so I think there is some work before the RC3. Please reopen the ticket
I hope it helps !
If you have any question feel free to ask me, my English is very poor and it's hard for me to explain things :)