Structure COMBOBOXINFO
  cbSize.l
  rcItem.Rect
  rcButton.Rect
  stateButton.l
  hwndCombo.l
  hwndItem.l
  hwndList.l
EndStructure

If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  ComboBoxGadget(1,10,10,100,20,#PB_ComboBox_Editable)
  
  cbi.COMBOBOXINFO\cbSize = SizeOf(COMBOBOXINFO)
  GetComboBoxInfo_(GadgetID(1),@cbi)
  SendMessage_(cbi\hwndItem,#EM_SETPASSWORDCHAR,'*',0)
Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf