转帖http://www.bczs.net luojx(大鱼儿) 的
<HTML>
<head><title>ListBox</title>
</head>
<body>
<select name="select"style="position:absolute; left: 10px; top: 10px; width: 120px; height: 18px; clip: rect(0 120 18 100)" id="select" onchange="textfield.value=select.value;textfield.select()">
<option value="aaaaaaaa">aaaaaaaa</option>
<option value="bbbbbbbb">bbbbbbbb</option>
<option value="cccccccc">cccccccc</option>
</select>
<input type="text" style="position:absolute; left: 10px; top: 10px; width: 100px; height: 20px" name="textfield">
</body>
</HTML>