For example changing the highlighted index to be the first possible in SuggestAppend AutoCompleteMode.
As a developer I would like to be able to implement a custom highlighting logic of the items in the DropDown portion of the control so that I could implement a "best" matched item highlighting.
Add a possibility to set minimum populate delay to the control. It would be useful if a property like MinimumPopulateDelay is available to be set which would cause the populating of items to be delayed. Such feature would be helpful for cases when making requests to web server etc.
Make it possible to override the functionality of keystrokes in the control. A useful case is when placing the control inside RadGridView's CellEditTemplate and wanting to leave cell editing mode by pressing the escape keyboard key.