combobox自動展開及關閉

新增cxcombobox，並加上item值，再加入下列事件：

procedure TForm1.cxComboBox1MouseEnter(Sender: TObject);
begin
  cxComboBox1.DroppedDown:=true;
end;

procedure TForm1.FormMouseEnter(Sender: TObject);
begin
  cxComboBox1.DroppedDown:=false;
end;