function showError(errormessage, field, formid) {
	if (formid==null) { formid = ""; } else { formid = "_"+formid; }
	var error = document.getElementById("error"+formid);
	if (error!=null) {
		error.innerHTML = errormessage;			
		error.style.display = "block"; 
		// extra
		if (field!=null){
			var inputfield = document.getElementById(field);
			if (inputfield.value=='E-mailadres') { inputfield.value=''; }
 		}
 	}
	
}			

function checkForm(	notEmptyFields, formid ) {
	if (formid==null) { formid = ""; } else { formid = "_"+formid; }
	var letop = document.getElementById("letop"+formid);
	var error = document.getElementById("error"+formid);

	var valid = true;
	//
	for (i=0; i<notEmptyFields.length; i++) { 
		// document.getElementById(notEmptyFields[i]).className = "";
		// document.getElementById(notEmptyFields[i]).onfocus = function() {};
		
  	if (document.getElementById(notEmptyFields[i]).value=="") {
  		if (valid) {
  			// Geef het eerste foute veld focus
  			document.getElementById(notEmptyFields[i]).focus();
  		}
  		// document.getElementById(notEmptyFields[i]).className = "inputerror";
  		valid = false;
    } 
  } 
  
	if (error!=null) {
		error.style.display = "none"; 
	}

	if (letop!=null) {
  	if (!valid) { 
  		// document.getElementById("letop").style.visibility = "visible";
  		letop.style.display = "block"; 
		}
		else {
  		// document.getElementById("letop").style.visibility = "hidden";
  		letop.style.display = "none"; 
		}
	}
  return (valid);
}