function $(id)
{
	return document.getElementById(id);
}

//イベントリスナー登録
function registerEventListener(element, eventType, listener)
{
	if(element.addEventListener){				//DOM
		element.addEventListener(eventType, listener, false);
	} else if(element.attachEvent){				//IE
		element.attachEvent("on" + eventType,
			function(event){
				listener.call(element, window.event);
			}
		);
	} else {
		element["on" + eventType] = listener;
	}

	return true;
}

var scrollTopLast = null;

function scrollUp()
{
	var scrollTop  = document.body.scrollTop  || document.documentElement.scrollTop;

	if(!scrollTopLast || scrollTopLast > scrollTop)
		window.scrollTo(0, scrollTop - scrollTop / 8);

	if(scrollTop != 0){
		scrollTopLast = scrollTop;
		window.setTimeout(scrollUp, 20);
	} else {
		scrollTopLast = null;
	}
}

function onClick_backToTop()
{
	scrollUp();
}

function onLoad()
{
	var buttonBackToTop = $("button_backtotop");

	if(buttonBackToTop)
		registerEventListener(buttonBackToTop, "click", onClick_backToTop, false);
}

registerEventListener(window, "load", onLoad, false);


//-----

function openSlideWindow(file)
{
	window.open("implant/casereports/" + file, "www_watanabekai_org_slide", "width=850,height=650,location=yes,scrollbars=yes");
}