function?getByclass(clsName,parent){
	var?oParent=parent?document.getElementById(parent):document,
		eles=[],
		elements=oParent.getElementsByTagName('*');

	for(var?i=0;i<elements.length;i++){
		if(elements[i].className==clsName){
			eles.push(elements[i]);
		}
	}
	return?eles;
}

window.onload=drag;

function?drag(){
	var?oTiltle=getByclass('login_logo_webqq','loginPanel')[0];
	oTiltle.onmousedown=fnDown;
}

function?fnDown(event){
	event=event?||?window.event;
	var?oDrag=document.getElementById('loginPanel'),
	//光標按下時光標和面板之間的距離
	disX=event.clientX-oDrag.offsetLeft,
	disY=event.clientY-oDrag.offsetTop;	
	//移動
	document.onmousmove=function(event){
		event=event?||?window.event;
		fnMove(event,disX,disY);
	}
}

function?fnMove(e,posX,posY){
	var?oDrag=document.getElementById('loginPanel'),
		l=e.clientX-posX,
		t=e.clientY-posY;
	oDrag.style.left=l+'px';
	oDrag.style.top=t+'px';
}