;Autor: klaver

EnableExplicit

Define wc.WNDCLASSEX
Define n

wc.WNDCLASSEX\cbSize = SizeOf(WNDCLASSEX)
GetClassInfoEx_(GetModuleHandle_(0), @"ComboBox", @wc)
Global PrevItm.i, LastKey.i, *Text=AllocateMemory(128), CBCB = wc\lpfnWndProc

Procedure ComboProc(hWnd, uMsg, wParam, lParam)
  Protected OldProc
  
  OldProc = GetProp_(hWnd, "MyCB")
  Select uMsg
    Case #WM_KEYDOWN
      LastKey = wParam
    Case #WM_NCDESTROY
      RemoveProp_(hWnd, "MyCB")
  EndSelect
  ProcedureReturn CallWindowProc_(OldProc, hWnd, uMsg, wParam, lParam)
EndProcedure

Procedure WinCallback(hWnd, uMsg, wParam, lParam)
  Protected *lpdis.DRAWITEMSTRUCT
  Protected Var
  Protected i
  
  Select uMsg
    Case #WM_DRAWITEM
      *lpdis.DRAWITEMSTRUCT = lParam : SetBkMode_(*lpdis\hDC, #TRANSPARENT)
      If *lpdis\CtlType = #ODT_COMBOBOX
        If *lpdis\itemState & #ODS_SELECTED
          If CallWindowProc_(CBCB, *lpdis\hwndItem, #CB_GETITEMDATA, *lpdis\itemID, 0);SendMessage_()
            *lpdis\CtlType = GetSysColorBrush_(#COLOR_BTNFACE)
          Else
            *lpdis\CtlType = GetSysColorBrush_(#COLOR_HIGHLIGHT)
          EndIf
        Else
          *lpdis\CtlType = GetSysColorBrush_(#COLOR_WINDOW)
        EndIf
        FillRect_(*lpdis\hDC, *lpdis\rcItem, *lpdis\CtlType) : *lpdis\rcItem\left+4
       
        CallWindowProc_(CBCB, *lpdis\hwndItem, #CB_GETLBTEXT, *lpdis\itemID, *Text);SendMessage_()
       
        If CallWindowProc_(CBCB, *lpdis\hwndItem, #CB_GETITEMDATA, *lpdis\itemID, 0);SendMessage_()
          SetTextColor_(*lpdis\hDC, #Gray);GetSysColor_(#COLOR_GRAYTEXT)
        EndIf
        DrawText_(*lpdis\hDC, *Text, -1, *lpdis\rcItem, #DT_NOCLIP|#DT_VCENTER|#DT_SINGLELINE)
        SetTextColor_(*lpdis\hDC, GetSysColor_(#COLOR_WINDOWTEXT))
      EndIf
    Case #WM_COMMAND
      Select (wParam>>16) & $FFFF;HIWORD
        Case #CBN_SELCHANGE
          Var = CallWindowProc_(CBCB, lParam, #CB_GETCURSEL, 0, 0);SendMessage_()
          If Var <> PrevItm
            If CallWindowProc_(CBCB, lParam, #CB_GETITEMDATA, Var, 0);SendMessage_()
              If LastKey = 38 Or LastKey = 37
                For i=Var-1 To 0 Step -1
                  If CallWindowProc_(CBCB, lParam, #CB_GETITEMDATA, i, 0) = #False
                    PrevItm = i : Break
                  EndIf
                Next
              ElseIf LastKey = 40 Or LastKey = 39
                For i=Var+1 To CallWindowProc_(CBCB, lParam, #CB_GETCOUNT, 0, 0)-1
                  If CallWindowProc_(CBCB, lParam, #CB_GETITEMDATA, i, 0) = #False
                    PrevItm = i : Break
                  EndIf
                Next
              EndIf
              CallWindowProc_(CBCB, lParam, #CB_SETCURSEL, PrevItm, 0);SendMessage_()
            Else
              PrevItm = Var
            EndIf
          EndIf
        Case #CBN_DROPDOWN
          LastKey = 0
      EndSelect
  EndSelect
  ProcedureReturn #PB_ProcessPureBasicEvents
EndProcedure

If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  ComboBoxGadget(1,10,10,200,20,#CBS_OWNERDRAWFIXED)
  
  For n=1 To 10
    AddGadgetItem(1,-1,"ComboBox Item "+Str(n),0,0)
  Next
  
  SendMessage_(GadgetID(1), #CB_SETITEMDATA, 3, #True);DISABLE ITEM
  SendMessage_(GadgetID(1), #CB_SETITEMDATA, 4, #True);DISABLE ITEM
  SendMessage_(GadgetID(1), #CB_SETITEMDATA, 9, #True);DISABLE ITEM
  SetProp_(GadgetID(1), "MyCB", SetWindowLong_(GadgetID(1), #GWL_WNDPROC, @ComboProc()))
  SetWindowCallback(@WinCallback(), 0)
  
  SetGadgetState(1,0)
  
Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf