prototype wrapper for YUI Dom utilities

http://chunghe.googlepages.com/prototype.wrapper.for.YUI.Dom.utilit.htm
用prototype把常用的一些 YUI Dom utilities (getRegion, getXY, getViewportHeight/getViewportWidth, getDocumentScrollTop/getDocumentScrollLeft)重寫一次，還是比較習慣YUI的naming convention，順便熟悉一下在prototype的哪些function mapping到YUI的哪些function。
值得一提的是 document.viewport.getDimensions().width;這個會把viewport width多算'17px'，之前在lightbox.js也有遇到一樣的問題，不是很確定，所以用了YUI的code把這部分補起來。另外YUI在IE底下，getXY在X與Y都多算了'2px'，prototype算起來倒是正確的。

var PUD = {
    getXY: function(ele){
        var ele = $(ele);
        var pos = ele.positionedOffset();
        return [pos.left, pos.top];
    },

    getRegion: function(ele){
        var ele = $(ele);
        var pos = ele.positionedOffset();
        var t   = pos[1]; 
        var r   = pos[0] + ele.offsetWidth;
        var b   = pos[1] + ele.offsetHeight;
        var l   = pos[0];
        return [t, r, b, l];
    },

    getViewportHeight: function(ele){
        return document.viewport.getDimensions().height;
    },

    getWrongViewportWidth : function(ele){
        // belowing method provided by prototype has '17px' margin error
        return document.viewport.getDimensions().width;
    },

    getViewportWidth : function(ele){
        // belowing method provided by prototype has '17px' margin error
        //return document.viewport.getDimensions().width;
        var width = self.innerWidth;
        var mode  = document.compatMode;

        if (mode || Prototype.Browser.IE) { // IE, Gecko, Opera
            width = (mode == 'CSS1Compat') ?
            document.documentElement.clientWidth : // Standards
            document.body.clientWidth; // Quirks
        }
        return width;
    },

    getDocumentScrollLeft : function(ele){
        return document.viewport.getScrollOffsets()[0];
    },

    getDocumentScrollTop : function(ele){
        return document.viewport.getScrollOffsets()[1];
    }
}