var nowactive='';
var old='';
function active(im){
	old = nowactive;
	nowactive = im;
	document[im].src = 'img/btn/' + im + '_s.gif';
}
function flipoff(im){
	if (nowactive!=im){
		document[im].src = 'img/btn/' + im + '.gif';
	}
}
function flipon(im){
	document[im].src = 'img/btn/' + im + '_s.gif';
}

var myimg=new Array();
function preloadimg(){
	for (i=0;i<preloadimg.arguments.length;i++){
		myimg[i]=new Image();
		myimg[i].src=preloadimg.arguments[i];
	}
}
preloadimg("img/btn/home_s.gif", "img/btn/margry_s.gif", "img/btn/woningen_s.gif", "img/btn/app_s.gif", "img/btn/uti_s.gif", "img/btn/contact_s.gif", "img/btn/login_s.gif");

function checkform(form) {
    for (var x=0; form.elements[x]; x++ ) {
		
		
		
		if(form.elements[x].alt == "verplicht") {

//		alert( form.elements[x].id );
//		alert( form.elements[x].alt );
//		alert( form.elements[x].checked );

			if ( form.elements[x].id == "voorwaarde" ) {
//		alert( form.elements[x].id );
//		alert( form.elements[x].alt );
//		alert( form.elements[x].checked );
				if (!form.elements[x].checked){
			        alert( "Om een aanvraag te kunnen verwerken moet u instemmen met de voorwaarde!" );
        		    form.elements[x].focus();
		            return false ;
        	    }
			}

			if (form.elements[x].value == ""){
	        alert( "U heeft het verplichte veld '" + form.elements[x].id + "' niet ingevuld." );
            form.elements[x].focus();
            return false ;
            }
        }
    }        
}