function Cover(){
	this.formDiv=null;	 		//
	//初始化共享变量
	if(typeof Cover._initShareVar == "undefined"){
		Cover.prototype.instanceCount=0; //初始化实例数
		Cover.prototype.instanceArray=new Array(); //保存实例数组
		Cover._initShareVar=true;
	}
	Cover.prototype.instanceCount++;
	this.hwnd=Cover.prototype.instanceCount; //窗口句柄用于窗口代码回调使用
	Cover.prototype.instanceArray[this.hwnd]=this; //保存实例引用
	//变量初始化完毕
	
	//初始化共享方法用于减少内存使用
	if(typeof Cover._initialized == "undefined"){
		Cover.prototype.show=function(){ //显示窗口
		if(this.formDiv==null){
				this.formDiv=document.createElement("div");
				this.formDiv.style.left=((top.document.body.scrollWidth)-500)/2; //window.event.clientX;
				this.formDiv.style.top=((top.document.body.scrollHeight)-500)/2;  //window.event.clientX;
				this.formDiv.style.position="absolute";
				this.formDiv.style.border="0px solid #A6C9E1";
				this.formDiv.style.background="#ffffff";
				this.formDiv.style.zIndex="9999";
				document.body.appendChild(this.formDiv);
				var objStyle = this.formDiv.style;
				objStyle.display = "block";
				objStyle.margin = "0px";
				objStyle.padding = "0px";
				objStyle.top = "0px";
				objStyle.left = "0px";
				objStyle.width = top.document.body.scrollWidth + "px";
				objStyle.height = top.document.body.scrollHeight + "px";
				objStyle.position = "absolute";
				objStyle.zIndex = "99";
				objStyle.background = "#000000";
				objStyle.filter = "alpha(opacity=40)";
				objStyle.opacity = 40/100;
				objStyle.MozOpacity = 40/100;
			}else{
				this.formDiv.style.display="";
			}
				var allselect = document.getElementsByTagName("select");
				if(allselect){
					for (var i=0; i<allselect.length; ++i)
					{
						allselect[i].style.visibility = "hidden";
					}
				}
		}
		
		Cover.prototype.hide=function(){ //隐藏窗口
			var objCover=this.formDiv;
			if (objCover){
				objCover.style.display = "none";
			}
			var allselect = document.getElementsByTagName("select");
			for (var i=0; i<allselect.length; ++i)
			{
				allselect[i].style.visibility = "visible";
			}
		}
		
		//静态方法调用函数
		Cover.CallFunc=function(pHwnd,pFuncName,pPara){
			if(pFuncName=="show"){
				Cover.prototype.instanceArray[pHwnd].show();
			}else if(pFuncName=="hide"){
				Cover.prototype.instanceArray[pHwnd].hide();
			}
		};
		Cover._initialized = true; 
	}	
}