We all know IE is weird:
<input id="mytestinput" onclick="this.style.backgroundImage='url(http://blog.csdn.net/images/authorship.gif)';" type="button" value="change background image" />
<script>
document.getElementById('mytestinput').attachEvent(
'onpropertychange', function () { alert(event.propertyName); });
</script>
'){kind=link}
click the button will alert twice.
If u set backgroundImage to 'none', it will also alert twice, however, set to ''(empty string), will only once...