function check_supporter(){
new Ajax.Request("/webcom/ajax_mitmach.php", {method: "post",parameters: {action:'confirm', id: document.getElementById("uid").value},
onSuccess: function(response){
      if (response.responseText == true)
      {
       	document.getElementById("login").submit();
      }
      else
      {
       	tb_show(null, 'http://mitmachen.fdp.de/mitmacharena/popup_register.php?myfdp_user=true&width=425&height=350', false);
      };
      
    },
 onFailure: function(){ alert('Something went wrong!') }
})
}