Images  = new Array();
NImages = 0;

alfa = (   ((navigator.appName == "Netscape") 
            && (parseInt(navigator.appVersion) >= 3 ))
        || ((navigator.appName == "Microsoft Internet Explorer")
            && (parseInt(navigator.appVersion) >= 4 )) );

function preloadImg(src)
{
    Images[NImages] = new Image();
    Images[NImages].src = src;
    NImages++;
	
}
  
function preloadAllImages()
{
    if ( alfa )
    {
	var tail = "0.gif";
	var i;
	for ( i = 0; i < document.images.length; i++ )
	{
	    var src = document.images[i].src;
	    if ( src.toLowerCase().lastIndexOf(tail) == src.length - 5 )
	    {
		preloadImg(src.substring(0, src.length - 5) + "1.gif");
	    }
	}
    }
}



function activateButton(id)
{
    if ( alfa )
    {
	var src  = document.images[id].src;
	var tail = "0.jpg";
	if ( src.toLowerCase().lastIndexOf(tail) == src.length - 5 )
	{
	    document.images[id].src = src.substring(0, src.length - 5) + "1.jpg";
	    return true;
	}
    }
    return false;
}

function deactivateButton(id)
{
    if ( alfa )
    {
	var src  = document.images[id].src;
	var tail = "1.jpg";
	if ( src.toLowerCase().lastIndexOf(tail) == src.length - 5 )
	{
	    document.images[id].src = src.substring(0, src.length - 5) + "0.jpg";
	    return true;
	}
    }
    return false;
}