var aImgPreloader = new Array;

var urlRoot="../images/wrpr/";

aImgPreloader[aImgPreloader.length] = new Array('sandiego',urlRoot+'cities_sandiego.gif',urlRoot+'cities_sandiego_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('seattle',urlRoot+'cities_seattle.gif',urlRoot+'cities_seattle_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('phoenix',urlRoot+'cities_phoenix.gif',urlRoot+'cities_phoenix_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('philadelphia',urlRoot+'cities_philadelphia.gif',urlRoot+'cities_philadelphia_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('chicago',urlRoot+'cities_chicago.gif',urlRoot+'cities_chicago_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('sanfrancisco',urlRoot+'cities_sanfrancisco.gif',urlRoot+'cities_sanfrancisco_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('washingtondc',urlRoot+'cities_washingtondc.gif',urlRoot+'cities_washingtondc_mo.gif');
aImgPreloader[aImgPreloader.length] = new Array('losangeles',urlRoot+'cities_losangeles.gif',urlRoot+'cities_losangeles_mo.gif');

// load up image container object based on previous array
var oImgContainer = new Object;
for(i=0;i<aImgPreloader.length;i++){
	if(document.images){
		oImgContainer[aImgPreloader[i][0]] = new Image;
		oImgContainer[aImgPreloader[i][0]].src = aImgPreloader[i][1];
		oImgContainer[aImgPreloader[i][0] + 'On'] = new Image;
		oImgContainer[aImgPreloader[i][0] + 'On'].src = aImgPreloader[i][2];
	}
}

// rollover function
// image name (sImg) corresponds with aImgPreloader and name attribute of tag
function roll(sImg,bOver){
	if(document.images){
		if (bOver) {
			document.images[sImg].src = oImgContainer[sImg + 'On'].src;
		} else {
			document.images[sImg].src = oImgContainer[sImg].src;


		}
	}
}

function showTheBook(){
	document.getElementById("navcontsub_thebook").style.visibility='visible';	
}
function hideTheBook(){
	document.getElementById("navcontsub_thebook").style.visibility='hidden';	
}

function showCollaboration(){
	document.getElementById("navcontsub_collaboration").style.visibility='visible';	
}
function hideCollaboration(){
	document.getElementById("navcontsub_collaboration").style.visibility='hidden';	
}

function showResources(){
	document.getElementById("navcontsub_resources").style.visibility='visible';	
}
function hideResources(){
	document.getElementById("navcontsub_resources").style.visibility='hidden';	
}