function more(myPage, windowName, myWidth, myHeight, resize){
	LeftPosition= (screen.width*0.5)-(myWidth*0.5);
	TopPosition= (screen.height*0.4)-(myHeight*0.5);
	window.open(myPage, windowName, 'width='+myWidth+',height='+myHeight+',top='+TopPosition+',left='+LeftPosition+',scrollbars=yes,location=no,directories=no,status=no,menubar=no,toolbar=no,resizable=' + resize);
}

function changeNav(navName){
	if (navName != 'nav_a') document.getElementById('nav_a').className='hiddenTable';
	if (navName != 'nav_b') document.getElementById('nav_b').className='hiddenTable';
	document.getElementById(navName).className='visibleTable';
}