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.

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