What I want is probably a pretty common request, but I would like to know if it can be managed with these controls (or any other pre-built ones). I've used AJAX in the past, but not for this.
I want to have 'Br' and have my databound dropdownlist filtered to only show "Brandon", "Brittany", etc. I can search and find the top-most matching one (list is alphabetical) with the listsearchextender or the combobox. I can only show the matches with the autocomplete extender and a textbox. But I want the drop-down select (not just type-in) to be available, and, because the list is long, the filtering ability.
If there's a way to force the dropdown list to always appear below (even when there isn't a lot of space), I can probably use the listboxextender. But because the list is long, and the control is in the middle of the page, the list pops up and covers the prompt, so the user can't see what they've already typed (user may need to backspace, etc.).