Transparent ComboLBox

[adzzzz]

I'm using the following code in an attempt to make a the listbox of a combobox transparent, with no luck tho. Add a combo to a form and try it please. It seems to just 'crash' the list.

Option Explicit
 
Private Declare Function GetComboBoxInfo Lib "user32.dll" _
  (ByVal hwndCombo As Long, _
  ByRef pcbi As PCOMBOBOXINFO) As Long
  
Private Declare Function SetWindowLong Lib "user32.dll" Alias "SetWindowLongA" _
  (ByVal hwnd As Long, _
  ByVal nIndex As Long, _
  ByVal dwNewLong As Long) As Long
  
Private Declare Function GetWindowLong Lib "user32.dll" Alias "GetWindowLongA" _
  (ByVal hwnd As Long, _
  ByVal nIndex As Long) As Long
     
Private Declare Function SetLayeredWindowAttributes Lib "user32.dll" _
  (ByVal hwnd As Long, _
  ByVal crKey As Long, _
  ByVal bAlpha As Byte, _
  ByVal dwFlags As Long) As Long
     
Private Type RECT
  Left As Long
  Top As Long
  Right As Long
  Bottom As Long
End Type
 
Private Type PCOMBOBOXINFO
  cbSize As Long
  rcItem As RECT
  rcButton As RECT
  stateButton As Long
  hwndCombo As Long
  hwndItem As Long
  hwndList As Long
End Type
 
Private Const GWL_EXSTYLE As Long = -20
Private Const LWA_ALPHA As Long = &H2
Private Const WS_EX_LAYERED As Long = &H80000
 
Private Sub Form_Load()
  Combo1.AddItem "moo"
  Combo1.AddItem "meep"
  Combo1.AddItem "baaa"
 
  Dim pcbi As PCOMBOBOXINFO, lRet As Long
  
  pcbi.cbSize = Len(pcbi)
  
  lRet = GetComboBoxInfo(Combo1.hwnd, pcbi)
  
  Call SetWindowLong(pcbi.hwndList, GWL_EXSTYLE, GetWindowLong(pcbi.hwndList, GWL_EXSTYLE) Or WS_EX_LAYERED)
  Call SetLayeredWindowAttributes(pcbi.hwndList, 0, 50, LWA_ALPHA)
End Sub

Cheers, adehh.