代码示例：（标识：dhtm_form_bg_textarea）
<html>
<head>
<script type="text/javascript">
function bgChange(bg)
{
document.getElementById('x').style.background="url(" + bg + ")"
}
</script>
</head>
<body>
<p>本例演示如何向 textarea 插入背景图像。</p>
<p>请把鼠标移动到图像上，textarea 会获得一幅背景图像：</p>
<table width="300" height="100">
<tr>
<td onmouseover="bgChange('/static/demo/images/eg_bg_03.gif')"
background="/static/demo/images/eg_bg_03.gif"></td>
<td onmouseover="bgChange('/static/demo/images/eg_bg_04.gif')"
background="/static/demo/images/eg_bg_04.gif"></td>
</tr>
</table>
<form>
<textarea id="x" rows="5" cols="20">
This example can not be edited
because our editor uses a textarea
for input,
and your browser does not allow
a textarea inside a textarea.
