'API Deklarieren
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal _
  hWnd As Long, _
  ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
 
'Konstante für API deklarieren
Private Const CB_SHOWDROPDOWN = &H14F
Private Const CB_GETDROPPEDSTATE = &H157
 
'Combo öffnen
Call SendMessage(cmb.hWnd, CB_SHOWDROPDOWN, 1, ByVal 0&)
 
'Zustand der Combo abfragen
return = SendMessage(cmb.hWnd, CB_GETDROPPEDSTATE, 0, 0)