anchor.diff:  
   procedure TfpgAbstractComboBox.DoDropDown;
   var
  -  ddw: TDropDownWindow;
  +//  ddw: TDropDownWindow;
  +  ddw: TMyTestWindow;
     rowcount: integer;
   begin
     if (not Assigned(FDropDown)) or (not FDropDown.HasHandle) then
     begin
       FreeAndNil(FDropDown);
       OriginalFocusRoot := FocusRootWidget;
  -    FDropDown       := TDropDownWindow.Create(nil);
  -    ddw := TDropDownWindow(FDropDown);
  +//    FDropDown       := TDropDownWindow.Create(nil);
  +
  +    ddw := TMyTestWindow.Create(nil, self);
  +    FDropDown := TMyTestWindow(ddw);
  +    ddw.Height := 200;
  +
  +//    ddw := TDropDownWindow(FDropDown);
       ddw.Width := Width;
       // adjust the height of the dropdown
       rowcount := FItems.Count;
  
positive.code:   case keycode of
  
      keyDown:
         begin
           FocusItem := FocusItem + 1;
           hasChanged := True;
         end;
  
      keyUp:
         begin
           FocusItem := FocusItem - 1;
           hasChanged := True;
         end;
  
      else
      begin
        Consumed := False;
      end;
    end;
  
    if consumed then
  
negative.code:       rowcount := FDropDownCount;
      if rowcount < 1 then
        rowcount := 1;
  //-----
      ddw.Height            := (ddw.ListBox.RowHeight * rowcount) + 4;
  //    ddw.ListBox.Height    := ddw.Height;   // needed in follow focus, otherwise, the default value (80) is used
  //    ddw.CallerWidget      := self;
  //    ddw.ListBox.OnSelect  := @InternalListBoxSelect;
  
      // Assign combobox text items to internal listbox and set default focusitem
  //    ddw.ListBox.Items.Assign(FItems);
  //    ddw.ListBox.FocusItem := FFocusItem;
  
      ddw.DontCloseWidget := self;  // now we can control when the popup window closes
      ddw.ShowAt(Parent, Left, Top + Height);      // drop the box below the combo
  //    ddw.ListBox.SetFocus;
    end
    else
    begin
      FBtnPressed := False;
  //    ddw := TDropDownWindow(FDropDown);
      ddw := TMyTestWindow(FDropDown);
      ddw.Close;
      FreeAndNil(FDropDown);
    end;
  