UI/dialog jump down when dragged in MSIE

when the page is scrolled down and then an ui dialog is being opened, trying to move it will cause it to "jump" down the page.

here's a complete sample (scroll down and click "open").

http://jsfiddle.net/77BMY/1/

this bug doesn't not occur in version 1.10.2, and happens for all versions of ie.

thanks,

Roey