// === DropDownCount === //
procedure THIComboBox._OnDropDown( Sender: PObj );
var
  CB: PControl;
  IC: Integer;
  H: Integer;
begin
  CB := PControl( Sender );
  IC := CB.Count;
  if IC > _prop_DropDownCount then IC := _prop_DropDownCount;
  if IC < 1 then IC := 1;
  
//  if (GetComCtlVersion and $FFFF0000) shr 16 >= 6 then
    CB.Perform(CB_SETMINVISIBLE, IC, 0);   
//  begin
    H := CB.Perform(CB_GETITEMHEIGHT, 0, 0);
    MoveWindow(CB.Handle, CB.Left, CB.Top, CB.Width, H * (IC + 2) + 2, false);
//  end
end;