以下几个函数，哪个几个在ff下不行？怎么改？

[veardn]

<script language="javascript">
var onLeftSide = false;
function openCalendar() {
var objButton = event.srcElement;
var objDateTime = objButton.previousSibling;
if (objDateTime == null) try {
if (onLeftSide) objDateTime = objButton.parentElement.nextSibling.firstChild;
else objDateTime = objButton.parentElement.previousSibling.firstChild;
} catch (e) { objDateTime = objButton; }
var pos = screenOffset(objButton, window);
var width = 192;
var height = 260;
var left = onLeftSide ? pos.left : pos.left + objButton.offsetWidth - width;
var top = pos.top + objButton.offsetHeight;
var url = "demo.html";
var rt = window.showModalDialog(url, objDateTime, "dialogWidth:" + width + "px; dialogHeight:" + height + "px; dialogLeft:" + left + "px; dialogTop:" + top + "px; center:no; help:no; edge:raised; resizable:no; scroll:no; status:no;");
if (rt == null) return;
else objDateTime.value = rt;
//modify();
}
function screenOffset(e, win) {
var b = e.document.body;
var pos = e == b ? { left : 0, top : 0 } : clientPos(e);
pos.top += top.screenTop;
pos.left += top.screenLeft;
for (var w = win || window; w != null && w.parent != null && w.parent != w; w = w.parent) {
var frm = findFrameElement(w);
var frmPos = clientPos(frm);
pos.left += frmPos.left;
pos.top += frmPos.top;
}
return pos;
}
function clientPos(e) {
var b = e.document.body;
if (e == b) return { left : -b.scrollLeft, top : -b.scrollTop };
with (e.getBoundingClientRect()) {
return { left : left - b.clientLeft, top : top - b.clientTop };
}
}

</script>
<input type="text" disabled><input type="button" value="..." onclick="openCalendar()" >
高手帮忙看看，怎么改

[xmliy]

    var onLeftSide = false;
    function openCalendar(e) {
        e = e || window.event;
        var objButton = e.srcElement ? e.srcElement : e.target;
        var objDateTime = objButton.previousSibling;
        if (objDateTime == null) try {
            if (onLeftSide) objDateTime = objButton.parentNode.nextSibling.firstChild;
            else objDateTime = objButton.parentNode.previousSibling.firstChild;
        } catch (e) { objDateTime = objButton; }
        var pos = screenOffset(objButton, window);
        var width = 192;
        var height = 260;
        var left = onLeftSide ? pos.left : pos.left + objButton.offsetWidth - width;
        var top = pos.top + objButton.offsetHeight;
        var url = "Test.htm";
        var rt = window.showModalDialog(url, objDateTime, "dialogWidth:" + width + "px; dialogHeight:" + height + "px; dialogLeft:" + left + "px; dialogTop:" + top + "px; center:no; help:no; edge:raised; resizable:no; scroll:no; status:no;");
        if (rt == null) return;
        else objDateTime.value = rt;
        //modify(); 
    }
    function screenOffset(e, win) {
        var b = document.body;
        var pos = e == b ? { left: 0, top: 0} : clientPos(e);
        pos.top += top.screenTop;
        pos.left += top.screenLeft;
        for (var w = win || window; w != null && w.parent != null && w.parent != w; w = w.parent) {
            var frm = findFrameElement(w);
            var frmPos = clientPos(frm);
            pos.left += frmPos.left;
            pos.top += frmPos.top;
        }
        return pos;
    }
    function clientPos(e) {
        var b = document.body;
        if (e == b) return { left: -b.scrollLeft, top: -b.scrollTop };
        with (e.getBoundingClientRect()) {
            return { left: left - b.clientLeft, top: top - b.clientTop };
        }
    } 

<input type="text" disabled> <input type="button" value="..." onclick="openCalendar(event)" >