// makes an ajax-request and checks username
	function checkusername(){
		if($('username').value != ''){
			if($('username_exists') != null){ $('username_exists').hide(); $('username_exists').remove(); }
			var param = 'username='+$('username').value;
			var url = './typo3conf/ext/mpm_alumni_registration/pi1/res/checkusername.php';
			var ajax = new Ajax.Updater('ajaxcontainer', url,{
							method: 'get',
							parameters: param,
							encoding: 'iso-8859-1',
							insertion: Insertion.Bottom,
							onLoading: function(){
										$('loader').appear({duration:.5});
									  },
							onLoaded: function(){
										$('loader').fade({duration: .1});
									  },
							onComplete: function(){
										$('username_exists').appear({duration: .5});
									  }
						});
			return false;
		}
	}