Different type of dropdownlist problem

Hello all forum member,

here i want the different type of dropdownlist which is like edittable combobox.i don't know is it possible or not?if it is possible then how if not how can i overcome the problem like that?
my problem is based on a control which working like textbox as well as dropdownlist or listbox.in there i can modify a item or select a item from there and also add a new item there.for example,in my application there are some item in databaseso i bind it in ddl then user can select a item from dropdown and show all the releted information as well as user can entry a new item in that control if he want.so that control working like textbox as well as ddl.
is it possible?please help me?
Thanking you.
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