ComboBox is an ASP.NET AJAX control that, like the AutoCompleteExtender, combines the flexibility of a TextBox with a list of options that users are able to choose from. It borrows many of its properties, behaviors, and naming conventions from the Windows Forms ComboBox control, and is derived from the same base class as the ListBox, BulletedList, and DropDownList web controls. In fact, a ComboBox is best described as a DropDownList that can be typed directly into like a TextBox.
<ajaxToolkit:ComboBox ID="ComboBox1" runat="server"
ItemInsertLocation="Append" ... >
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