var _blank_img_src = "/img/blank.gif";

function IsOldIE()
{
	return (/MSIE (5\.5|6).+Win/.test(navigator.userAgent));
}

function IsPNG(imgObject)
{
	return (/\.png$/.test(imgObject.src));
}

function MoveAsImg( img_src, img_dst )
{
	img_dst.src = img_src.src;
}

function MoveAsFilter( img_src, img_dst )
{
	img_dst.src = _blank_img_src;
	img_dst.runtimeStyle.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + img_src.src + "',sizingMethod='scale')";
}

function ChangeImg( img_id1, img_id2 )
{
	var img1 = document.getElementById( img_id1 );
	var img2 = document.getElementById( img_id2 );
	if( IsOldIE() && IsPNG(img2) ){
		MoveAsFilter( img2, img1 );
	}else{
		MoveAsImg( img2, img1 );
	}
}

// sizing_method (http://msdn2.microsoft.com/en-us/library/ms532920.aspx)
//   "image"
//   "crop"
//   "scale"
function fixPNG( element, sizing_method )
{
	var src;
	if (element.tagName=='IMG')
	{
		if (/\.png$/.test(element.src))
		{
			src = element.src;
			element.src = _blank_img_src;
		}
	}else{
		src = element.currentStyle.backgroundImage.match(/url\("(.+\.png)"\)/i);
		if (src)
		{
			src = src[1];
			element.runtimeStyle.backgroundImage="none";
		}
	}
	if (src) element.runtimeStyle.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + src + "',sizingMethod='" + sizing_method + "')";
}