var THM_scrollnavE;
var THM_scrollnavY;
var THM_scrollnavM;
var THM_scrollnavS;

function THM_scrollnavInit() {
	
	THM_scrollnavE = $('nav_1');
	THM_scrollnavY = THM_scrollnavE.getPosition().y;
	THM_scrollnavM = 0;
	THM_scrollnavS = new Fx.Elements( THM_scrollnavE, { link: 'cancel', duration: 'short' } );
	window.setTimeout( "THM_scrollnavCheck()", 500 );
}

function THM_scrollnavCheck() {

	var newM = Math.max( window.getScroll().y + 30 - THM_scrollnavY, 0 );
	if ( newM != THM_scrollnavM ) {
		THM_scrollnavS.start( { '0': { 'margin-top': newM } } );
		THM_scrollnavM = newM;
	}

	window.setTimeout( "THM_scrollnavCheck()", 500 );
}