ja jag tycker det
<script>
function setvalue(values) {
document.getElementById('posisi').value = values;
}
</script>
<div>
<table width="1023" height="248" border="1">
<tr>
<td>
<input type="button" onclick="setvalue(this.value);" value="A1.8" />
</td>
</tr>
</table>
</div>
<div class="popup_window_css" id="sample">
<table class="popup_window_css">
<tr class="popup_window_css">
<td class="popup_window_css">
<div class="popup_window_css_head">
<img src="images/close.gif" alt="" width="9" height="9" />Aksi</div>
<div class="popup_window_css_body">
<div style="border: 1px solid #808080; padding: 6px; background: #FFFFFF;">
<form method="post" action="">
<table>
<tr>
<td>Werehouse</td>
<tr>
<td>Posisi</td>
<td>
<input type='text' name="p" id="posisi" />
</td>
</tr>
<tr>
<td>Product ID</td>
<td>
<input type='text' name="id" />
</td>
</tr>
<tr>
<td>Product Name</td>
<td>
<input type='text' name="nama" />
</td>
</tr>
<tr>
<td>Production Date</td>
<td>
<input type='text' name="tgl" />
</td>
</tr>
<tr>
<td colspan='2' align='right'>
<input type='submit' value='Save'>
<input type='reset' value='Reset' />
<input type='button' value='view' onclick=\ "window.location.href='#';\"/>
</td>
</tr>
</table>
</div>
</div>
du kan se här http://jsfiddle.net/JLExZ/