Add option to enter new value that is independent from the data source or items.

When the AutoCompleteBox has a list of AutoCompleteItems, a drop-down (combo box) is displayed when typing. However, this combo box is not announced, and when you use the arrow keys to navigate through the items in the combo box, they are not announced as well.

NullText property should not be ignored when DropDownStyle property is DropDownList.  One shouldn't have to utilize the Text property or create a dummy object to simulate this behavior as discussed here:

https://www.telerik.com/forums/nulltext-property-doesn-t-work-in-raddropdown?actionMode=replyPost&postId=0a021bbb-f40a-4263-a1af-c87b33c17467

Please add!!!  I struggle with this whenever I'm using data bound drop downs.