特點：
1、兼容 IE6、FF、Opear（IE7還沒有機會測試）
2、拖動流暢
3、起點與終點之間有過渡，使移動更平滑(可調)
演示
/*
Author:misshjn
HomePage:http://www.happyshow.org
Date:2007-04-30
拖動開始
*/
function _getStyle(element,styleProp){
if (element.currentStyle){
var y = element.currentStyle[styleProp];
}else if (window.getComputedStyle){
var y = document.defaultView.getComputedStyle(element,null).getPropertyValue(styleProp.replace(/([A-Z])/g,"-$1").toLowerCase());
}
return y;
}
function _elementOnmouseDown(evt,blockID){
var obj, temp;
obj=document.getElementById(blockID);
var x = evt.clientX || evt.pageX;
var y = evt.clientY || evt.pageY;
obj.startX=x-obj.offsetLeft;
obj.startY=y-obj.offsetTop;
var d = document.createElement("div");
d.style.position = "absolute";
d.style.width = obj.clientWidth + parseInt(_getStyle(obj,"borderLeftWidth"),10) + parseInt(_getStyle(obj,"borderRightWidth")) -2 + "px";
d.style.height = obj.clientHeight + parseInt(_getStyle(obj,"borderTopWidth"),10) + parseInt(_getStyle(obj,"borderBottomWidth")) -2 + "px";
d.style.border = "1px dashed #666";
d.style.top = _getStyle(obj,"top");
d.style.left = _getStyle(obj,"left");
d.style.zIndex = "9999";
document.body.appendChild(d);
document.onmousemove=function(evt){
d.style.left= (evt?evt.pageX:event.clientX) - obj.startX + "px";
d.style.top= (evt?evt.pageY:event.clientY) - obj.startY + "px";
};
document.onmouseup=function(){
var objL = parseInt(_getStyle(obj,"left"),10);
var objT = parseInt(_getStyle(obj,"top"),10);
var obj2L = parseInt(d.style.left,10);
