When scroll down the page, the Raddropdown list did not close, instead the dropdown list follow to scroll action and appear in other area of the page. This happens for RadAutocompleteBox too.
Please check the attached images for more details.
We have provided a KB article for this issue: http://www.telerik.com/community/code-library/aspnet-ajax/combobox/attach-the-dropdown-to-the-input-element-while-scrolling-within-a-scrollable-container.aspx