function clearCallbackField(theField, fieldtext) {
	var f = theField;
	if (f.value == fieldtext) {
		f.value='';
	} else {
		if (f.value == '') {
		f.value = fieldtext;
		}
	}
}

function checkFormCallback(){
	document.getElementById('div_callback_unvalid').style.display = 'none';
	var valid = true;
	if(document.getElementById('callback_question').value == '' 
		|| document.getElementById('callback_question').value == 'Uw vraag'){
		valid = false;	
	}
	if(document.getElementById('callback_date').value == '' 
		|| document.getElementById('callback_date').value == 'dd/mm/jjjj'){
		valid = false;	
	}
	if(document.getElementById('callback_hour').value == '' 
		|| document.getElementById('callback_hour').value == 'hh:mm'){
		valid = false;	
	}
	if(document.getElementById('callback_phone').value == '' 
		|| document.getElementById('callback_phone').value == 'Uw telefoonnummer'){
		valid = false;	
	}
	if(!valid){
		document.getElementById('div_callback_unvalid').style.display = 'block';
	}else{
		var a = new ajaxCallback();
		a.setCallbackHandler(displayResponseMessage);
		a.sendCallbackForm({
			date:document.getElementById('callback_date').value,
			hour:document.getElementById('callback_hour').value,
			phone:document.getElementById('callback_phone').value,
			question:document.getElementById('callback_question').value.replace(/\n/g, '<br />')
			});
	}
}
function displayResponseMessage(msg){
	document.getElementById('div_form').style.display = 'none';
	document.getElementById('div_callback_thank_you').innerHTML = '<p>'+msg+'</p>';
	document.getElementById('div_callback_thank_you').style.display = 'block';
}