The following code will allow backspace in textbox not on form. This code works perfectly in IE7/8,FireFox,Chrome
<script language=javascript>
function cancelBack()
{
if ((event.keyCode == 8 ||
(event.keyCode == 37 && event.altKey) ||
(event.keyCode == 39 && event.altKey))
&&
(event.srcElement.form == null || event.srcElement.isTextEdit == false)
)
{
event.cancelBubble = true;
event.returnValue = false;
}
}
</script>
<body onkeydown=cancelBack()>