function check(waarde,wit) {
	var len = document.frm.elements.length;
	var totaal=0;
	for(var i=0;i<len;i++) {
		var e = document.frm.elements[i];
		if ((e.type == 'checkbox') && (e.checked)) {
			totaal+= 1;
		}
	}

	if(totaal>=12) {
		document.frm.opslaan1.disabled=0;
		document.frm.opslaan2.disabled=0;
	} else {
		document.frm.opslaan1.disabled=1;
		document.frm.opslaan2.disabled=1;
	}
	if(waarde=='start' && (totaal==0 ||totaal==12)) {
		document.getElementById('laag13').style.visibility='visible';
	} else {
		if(totaal>12) {
			if(waarde>0) {
				document.frm.elements['renner['+waarde+']'].checked=false;
				alert("U kunt maximaal 12 renners selecteren.");
			}
		} else {
			if(waarde>0) {
				if(document.frm.elements['renner['+waarde+']'].checked==true) {
					document.getElementById('rennerbalk'+waarde).className='geselecteerderenner';
				} else {
					if(wit==1) {
						document.getElementById('rennerbalk'+waarde).className='rennertransparant';
					} else {
						document.getElementById('rennerbalk'+waarde).className='rennerwit';
					}
				}
			}
		
			for(var i=0;i<14;i++) {
				if(totaal==i) {
					document.getElementById('laag'+i).style.visibility='visible';
				} else {
					document.getElementById('laag'+i).style.visibility='hidden';
				}
			}
		}
	}
}

function popwindow(xsize,ysize,url,align) {
	var wWidth, wHeight, wLeft, wTop;
	wWidth = xsize;
	if(ysize>0) {
		wHeight = ysize;
	} else {
		wHeight = wWidth*.75;
	}
	if(align=='center') {
		wLeft = (screen.width-wWidth)/2;
		wTop = (screen.height-wHeight)/2;
		var Scherm = window.open(url, '_blank', 'scrollbars=yes,width='+wWidth+',height='+wHeight+',left='+wLeft+',top='+wTop);
	} else {
		var Scherm = window.open(url, '_blank', 'scrollbars=yes,width='+wWidth+',height='+wHeight);
	}
	Scherm.focus();
}