function preload_images() {
	MM_preloadImages('/images/button1_over.jpg','/images/button2_over.jpg','/images/button3_over.jpg'
						,'/images/button4_over.jpg','/images/button5_over.jpg','/images/button6_over.jpg');
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function over(buttonNum) {
	var but = document.getElementById('button'+buttonNum);
	but.src='/images/button'+buttonNum+'_over.jpg';
}

function out(buttonNum) {
	var but = document.getElementById('button'+buttonNum);
	but.src='/images/button'+buttonNum+'.jpg';
}

function subover(buttonNum) {
	var but = document.getElementById('submenu'+buttonNum);
	but.className='submenu_sel';
}

function subout(buttonNum) {
	var but = document.getElementById('submenu'+buttonNum);
	but.className = '';
}