The RadDropDownTree control is a combination of a lightweight dropdown and a tree control.The approach with entries like in the RadAutoCompleteBox is used. Basically, an new entry is created as a resultof node's selection from the tree.
Some of the main features of the RadDropDownTree control include:
Various DataBindings including declarative binding, binding to Entity DataSource as well as Linq DataSource
Templates such as Header Template, Footer Template and Node Template.
Checkboxes that enable the user to choose between the different states - None, SingleCheck, TriState and CheckChildNodes.
EmptyMessage that will allow the developer to provide a hint (setting a message in the entry area) to the final user of the application.
There are also DropDownSettings that enable fine tuning of the control (OpenDropDownOnLoad that expands the dropdown after it is loaded on the page is one of them).