onmouseover - Can some one help me to find solution

Question

this piece of code work fine if size of "select option" is superior to 1. but if you try size="1" it doesn't work ??

`<script type="text/javascript">
     function affiche(param)
     {
        alert(param);
     }
  </script>

  <select id="lbVoitures" size="1">
      <option value="1" onmouseover="affiche(1)">Pigeot</option>
      <option value="2" onmouseover="affiche(2)">Reno</option>
      <option value="3" onmouseover="affiche(3)">Citron</option>
  </select>`

Answer 1

等待大神答复