AutoComplete functionality for Text box in WinForms

AutoCompleteStringCollection AutoComp = null;

txtFName.AutoCompleteMode = AutoCompleteMode.Suggest;
txtFName.AutoCompleteSource = AutoCompleteSource.CustomSource;

AutoComp.Add("AAAA");  
AutoComp.Add("BBBB");  
AutoComp.Add("GGGG");  

txtFName.AutoCompleteCustomSource = AutoComp;