var buttonOn = new Array();
var buttonOff = new Array();
var buttonActive = new Array();
var buttonActiveOn = new Array();
var imagePath = "images/";
var nav_active_status = "start";

function preloadImages()
{
	if (document.images) 
	{
		for (i =0; i<document.images.length;i++)
		{
			if (document.images[i].name.indexOf('_button')!=-1)
			{
				stopPoint = document.images[i].name.indexOf('_button');
				imageName =document.images[i].name.substring(0,stopPoint);
				
				buttonOn[document.images[i].name] = new Image();
				buttonOn[document.images[i].name].src = imagePath + imageName + '_on.gif';
				
				buttonOff[document.images[i].name] = new Image();
				buttonOff[document.images[i].name].src = imagePath + imageName + '_off.gif';
				
				buttonActive[document.images[i].name] = new Image();
				buttonActive[document.images[i].name].src = imagePath + imageName + '_active.gif';
				
				buttonActiveOn[document.images[i].name] = new Image();
				buttonActiveOn[document.images[i].name].src = imagePath + imageName + '_activeon.gif';
			}
		}
	}
}


function nav_highlight(which) {
	if(nav_active_status == which)
		document.images["nav_" + which + "_button"].src = buttonActiveOn["nav_" + which + "_button"].src;
	else
		document.images["nav_" + which + "_button"].src = buttonOn["nav_" + which + "_button"].src;
}

function nav_darken(which) {
	if(nav_active_status == which)
		document.images["nav_" + which + "_button"].src = buttonActive["nav_" + which + "_button"].src;
	else
		document.images["nav_" + which + "_button"].src = buttonOff["nav_" + which + "_button"].src;
}

function nav_active(which) {
	if(nav_active_status != "") {
		document.images["nav_" + nav_active_status + "_button"].src = buttonOff["nav_" + nav_active_status + "_button"].src;
	}
		nav_active_status = which;
	document.images["nav_" + which + "_button"].src = buttonActive["nav_" + which + "_button"].src;
}

function resetNav() {
	if(nav_active_status != "") {
	document.images["nav_" + nav_active_status + "_button"].src = buttonOff["nav_" + nav_active_status + "_button"].src;
		nav_active_status = "";
	}
}