enum AutoCompleteFlags : uint {

Enum AutoCompleteFlags As Integer

    AutoCompleteFlags dwFlags

Declare Function SHAutoComplete Lib "shlwapi.dll" (ByVal hWndEdit As IntPtr, ByVal dwFlags As AutoCompleteFlags) As Integer

AutoCompleteFlags

Int32 res = SHAutoComplete(textBox1.Handle, AutoCompleteFlags.SHACF_FILESYSTEM);