window.onload = function(){
	// Afzender
	captureEvent( 'afzendernaam', 'Afzender naam' );
	captureEvent( 'afzenderemail', 'Afzender email' );
	
	// Ontvanger
	captureEvent( 'ontvangernaam', 'Ontvanger naam' );
	captureEvent( 'ontvangeremail', 'Ontvanger email' );
	
	function captureEvent( elementId, elementValue )
	{
		var e = document.getElementById( elementId );
		if( e != null ){
			e.onfocus = function(){
				if( this.value == elementValue ){this.value = '';}
			}
			e.onblur = function(){
				if (this.value == '') {this.value = elementValue;}
			}
		}
	}
};