// IE6 画面ちらつき対策 //

try
{
	document.execCommand('BackgroundImageCache', false, true);
}
catch(e)
{
}

// ドロップダウン //

var DDSPEED = 1;
var DDTIMER = 1;

// main function to handle the mouse events //
function ddMenu(id, d)
{
	var h = document.getElementById(id + '-ddheader');
	var c = document.getElementById(id + '-ddcontent');
	clearInterval(c.timer);
	if (d == 1)
	{
		clearTimeout(h.timer);
		if (c.maxh && c.maxh <= c.offsetHeight)
		{
			return;
		}
		else if (!c.maxh)
		{
			c.style.display = 'block';
			c.style.height = 'auto';
			c.maxh = c.offsetHeight;
			c.style.height = '0px';
		}
		c.timer = setInterval(function(){ddSlide(c, 1)}, DDTIMER);
	}
	else
	{
		h.timer = setTimeout(function(){ddCollapse(c)}, 50);
	}
}

// collapse the menu //
function ddCollapse(c)
{
	c.timer = setInterval(function(){ddSlide(c, -1)}, DDTIMER);
}

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id)
{
	var h = document.getElementById(id + '-ddheader');
	var c = document.getElementById(id + '-ddcontent');
	clearTimeout(h.timer);
	clearInterval(c.timer);
	if (c.offsetHeight < c.maxh)
	{
		c.timer = setInterval(function(){ddSlide(c, 1)}, DDTIMER);
	}
}

// incrementally expand/contract the dropdown and change the opacity //
function ddSlide(c, d)
{
	var currh = c.offsetHeight;
	var dist;
	if (d == 1)
	{
		dist = (Math.round((c.maxh - currh) / DDSPEED));
	}
	else
	{
		dist = (Math.round(currh / DDSPEED));
	}
	if (dist <= 1 && d == 1)
	{
		dist = 1;
	}
	c.style.height = currh + (dist * d) + 'px';
	c.style.opacity = currh / c.maxh;
	c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
	if ((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1))
	{
		clearInterval(c.timer);
	}
}