function framecheck()
/*thank boss !!*/
{
   if ((navigator.appName).indexOf("Microsoft")!=-1) {
      var winWidth = document.body.offsetWidth; // Internet Explorer
   } else {
      var winWidth = window.innerWidth
   }   
   if(winWidth < 850){
	document.getElementById('mainbody').style.left = 0;
	document.getElementById('mainbody').style.marginLeft = 0;
   }
   
   if(winWidth >= 850){
	document.getElementById('mainbody').style.left = '50%';
	document.getElementById('mainbody').style.marginLeft = '-375px';
   }
}

function checkfields_v2()
{
var pass=true;
var alerttext="De volgende fouten zijn geconstateerd:"
var arguments=checkfields_v2.arguments;
if (arguments.length > 0)
 {
 for (i=0; i<(arguments.length-2); i+=3)
  {
  if (document.getElementById(arguments[i]).value=="")
   {
   alerttext+="\n- "+arguments[i+1]+" is verplicht";
   pass=false;
   }
  }
 }
if (pass==false)
 {
 alert(alerttext);
 return false;
 }
else
 {
 return true;
 }
}