function _addEventHandler(element,event,handler) {

var _tmp, _onevent;

if (!element||!event) return false;
if (element.addEventListener) element.addEventListener(event,handler,false);
else {
 _onevent = 'on'+event;
 if (element.attachEvent) element.attachEvent(_onevent,handler);
 else {
 _tmp=element[_onevent];
 element[_onevent] = typeof _tmp =='function' ? (function() { _tmp();handler(); }) : handler;
 }
}

}

function shownavi() {

document.getElementById('navitool').style.left=0;

}

function hidenavi() {

document.getElementById('navitool').style.left="-250px";
}

function initnavi() {
  _addEventHandler(document.getElementById('navitool'),'mouseover',shownavi)
  _addEventHandler(document.getElementById('navitool'),'mouseout',hidenavi)
}