Use the DropDown and DropUp events to notify your application when the drop-down portion of the control is shown or hidden. The DropDown and DropUp events are fired only if the control's Style property is DropDown or DropDownList. Use the hWndDropDown property to get the handle of the drop down window. The AutoDropDown property retrieves or sets a value that indicates whether the control's list automatically drops down once the user starts type into it.