function showTip(e){
event = window.event || e;
var div3 = document.getElementById( 'div3 ');
div3.style.display= "block ";
div3.style.left=event.clientX;
div3.style.top=event.clientY;
div3.style.position= "absolute ";
}
在FIREFOX中,ENENT要显示的传给函数
onmousemove= "showTip(event) "