RadDropDownButton provides a menu-like interface open from a button.
Each of the items of RadDropDownButton can be set to perform an action when clicked. In addition, the items can contain other items, allowing you to create any hierarchy that fits your needs of subitems.
To use RadDropDownButton, drag a RadDropDownButton on the surface of your form designer from the Toolbox. Like a standard button, you can control the displayed text by setting the Text property. Unlike a standard button, RadDropDownButton displays drop-down items when clicked; so handling the Click event of this button is not appropriate. Instead, work directly with the events for each item. To learn how to create and use items on a RadDropDownButton see Working with Telerik RadDropDownButton Items.
RadDropDownButton is visually indistinguishable from RadSplitButton, but there is an important programmatic distinction. On RadSplitButton the DefaultItem property indicates the item whose Click event should be triggered when the button is clicked. If you want a button that does something when clicked as well as when a selection is made from the menu, you should use a RadSplitButton instead of a RadDropDownButton.