//屏蔽鼠标右键、Ctrl+N、Shift+F10、F11、F5刷新、退格键
function   document.oncontextmenu(){event.returnValue=false;}//屏蔽鼠标右键
function   window.onhelp(){return   false}   //屏蔽F1帮助
function   document.onkeydown()
{
	if((window.event.altKey)&&
		((window.event.keyCode==37)||  //屏蔽   Alt+   方向键   ←
		(window.event.keyCode==39)))  //屏蔽   Alt+   方向键   →
	{
 // alert("不准你使用ALT+方向键前进或后退网页！");
		event.returnValue=false;
	}

	if((event.keyCode==8)||//屏蔽退格删除键
		(event.keyCode==116)||//屏蔽   F5   刷新键
		(event.ctrlKey   &&   event.keyCode==82)){   //Ctrl   +   R
		event.keyCode=0;
		event.returnValue=false;
	}
	if(event.keyCode==122){event.keyCode=0;event.returnValue=false;}//屏蔽F11
	if(event.ctrlKey   &&   event.keyCode==78)   event.returnValue=false;  //屏蔽   Ctrl+n
	if(event.shiftKey   &&   event.keyCode==121)event.returnValue=false;//屏蔽   shift+F10
	if(window.event.srcElement.tagName   ==   "A"   &&   window.event.shiftKey)  
    window.event.returnValue   =   false;  //屏蔽   shift   加鼠标左键新开一网页
	if((window.event.altKey)&&(window.event.keyCode==115))  //屏蔽Alt+F4
	{
		window.showModelessDialog("about:blank","","dialogWidth:1px;dialogheight:1px");
		return   false;
	}
}