jQuery dialog jumps on background ajax control update

We have a silverlight control inside jQuery modal dialog, to upload files. When files are uploaded, the page in background gets the update and refreshes the activity part of the page (e.g. $("#activity").html(dataFromServer)).

However when that part of the page is refreshed, the dialog jumps to top/bottom, on every refresh. This happens in both IE8 and Chrome. jQuery 1.4.4.

Are there any bugs in jQuery or what is happening?

UPD: Seem to be related to this (page content change -> scroll params (not position but...) changes -> dialog position changed) but I'm not sure. And still wonder how to fix without manual hacks in ajax events.

And, actually, I can fix the issue with

开发者_高级运维           $('my-selector').dialog('option', 'position', 'center');

after .html(data) BUT the dialog jumps to top then back, which is still ugly.

OK, ui.position was not included in the custom build (done not by me to give an excuse).