ListView Columns und OwnerDraw

[Nils_13]

Ich habe PBExListview weiterentwickelt:

Delphi-Quellcode:

private
  FColumnBrushColor : TColor;
  [...]

protected
  procedure WMDrawItem(var Message : TWMDrawItem); message WM_DRAWITEM; 
  [...]

published
  property ColumnBrushColor : TColor
      read FColumnBrushColor write FColumnBrushColor;
  [...]

[...]

procedure TColumnListView.WMDrawItem(var Message : TWMDrawItem);
var State     : TOwnerDrawState;
    SaveIndex : Integer;
begin
  with Message.DrawItemStruct^ do
  begin
    State := TOwnerDrawState(WordRec(LongRec(itemState).Lo));
    SaveIndex := SaveDC(hDC);
    FCanvas.Handle := hDC;
    FCanvas.Font   := Font;
    FCanvas.Brush.Color  := FColumnBrushColor;
    if itemID = DWORD(-1) then FCanvas.FillRect(rcItem)
    else DrawItem(Items[itemID], rcItem, State);
    FCanvas.Handle := 0;
    RestoreDC(hDC, SaveIndex);
  end;
  Message.Result := 1;
end;

Setzt man allerdings die Komponente auf die Form, tut sich nichts. Warum ?