var browser = navigator.appName;

document.onkeydown = browser == "Microsoft Internet Explorer" ? kpressed_IE : kpressed_others;

function kpressed_IE(e)
{
	if (!e) var e = window.event;
	if (e.keyCode)
	{
		keycode = e.keyCode;
		if ((keycode == 39) || (keycode == 37))
			window.event.keyCode = 0;
	}
	else
		keycode = e.which;
	
	change_page(keycode);
}

function kpressed_others(e)
{
	if (e.which)
		keycode = e.which;
	else
		keycode = e.keyCode;
	
	change_page(keycode);
}

function change_page(keycode)
{
	if (next_page != null && keycode == 39)
	{
		window.location = next_page;
		return false;
	}
	else if (previous_page != null && keycode == 37)
	{
		window.location = previous_page;
		return false;
	}
}

function drop_page(page)
{
	window.location = page;
}

function change_chapter(chapter)
{
	window.location = chapter;
}