var __isIE =  navigator.appVersion.match(/MSIE/);
var __userAgent = navigator.userAgent;
var __isFireFox = __userAgent.match(/firefox/i);
var __isFireFoxOld = __isFireFox && 
   (__userAgent.match(/firefox\/2./i) || __userAgent.match(/firefox\/1./i));
var __isFireFoxNew = __isFireFox && !__isFireFoxOld;

function __parseBorderWidth(width) {
    var res = 0;
    if (typeof(width) == "string" && width != null 
                && width != "" ) {
        var p = width.indexOf("px");
        if (p >= 0) {
            res = parseInt(width.substring(0, p));
        }
        else {
             //do not know how to calculate other 
             //values (such as 0.5em or 0.1cm) correctly now
             //so just set the width to 1 pixel
            res = 1; 
        }
    }
    return res;
}

//returns border width for some element
function __getBorderWidth(element) {
    var res = new Object();
    res.left = 0; res.top = 0; res.right = 0; res.bottom = 0;
    if (window.getComputedStyle) {
        //for Firefox
        var elStyle = window.getComputedStyle(element, null);
        res.left = parseInt(elStyle.borderLeftWidth.slice(0, -2));  
        res.top = parseInt(elStyle.borderTopWidth.slice(0, -2));  
        res.right = parseInt(elStyle.borderRightWidth.slice(0, -2));  
        res.bottom = parseInt(elStyle.borderBottomWidth.slice(0, -2));  
    }
    else {
        //for other browsers
        res.left = __parseBorderWidth(element.style.borderLeftWidth);
        res.top = __parseBorderWidth(element.style.borderTopWidth);
        res.right = __parseBorderWidth(element.style.borderRightWidth);
        res.bottom = __parseBorderWidth(element.style.borderBottomWidth);
    }
   
    return res;
}

//returns absolute position of some element within document
function getElementAbsolutePos(element) {
    var res = new Object();
    res.x = 0; res.y = 0;
    if (element !== null) {
        res.x = element.offsetLeft;
        res.y = element.offsetTop;
        
        var offsetParent = element.offsetParent;
        var parentNode = element.parentNode;
        var borderWidth = null;

        while (offsetParent != null) {
            res.x += offsetParent.offsetLeft;
            res.y += offsetParent.offsetTop;
            
            var parentTagName = offsetParent.tagName.toLowerCase();    

            if ((__isIE && parentTagName != "table") || 
                (__isFireFoxNew && parentTagName == "td")) {            
                borderWidth = __getBorderWidth(offsetParent);
                res.x += borderWidth.left;
                res.y += borderWidth.top;
            }
            
            if (offsetParent != document.body && 
                offsetParent != document.documentElement) {
                res.x -= offsetParent.scrollLeft;
                res.y -= offsetParent.scrollTop;
            }

            //next lines are necessary to support FireFox problem with offsetParent
               if (!__isIE) {
                while (offsetParent != parentNode && parentNode !== null) {
                    res.x -= parentNode.scrollLeft;
                    res.y -= parentNode.scrollTop;
                    
                    if (__isFireFoxOld) {
                        borderWidth = __getBorderWidth(parentNode);
                        res.x += borderWidth.left;
                        res.y += borderWidth.top;
                    }
                    parentNode = parentNode.parentNode;
                }    
            }

            parentNode = offsetParent.parentNode;
            offsetParent = offsetParent.offsetParent;
        }
    }
    return res;
}