anchor.diff:  part of nest_ui;
   
  +/** The purpose of this component is to display user notifications, such as when a user successfully logs in or incorrectly fills the form.
  +  * Such notifications usually appear on top of the page and disappear after some time. This component if flexible enough to
  +  * allow you to tweak for how long a notification should be displayed, whether it should stay there until user leaves the page (permanent),
  +  * and also tweak the message type (so that you can add CSS code to have different notification colors for different types of messages). 
  +  *
  +  * The best part of this component is that you can invoke the notification in two different ways: programmatically, by writing
  +  * Dart code and initializing the component or by having a DOM element in your DOM. The latter is convenient to automatically
  +  * display messages on page load and is, probably, the most common way in which this component is going to be used.
  +  */
   class SimpleNotificationComponent extends Component with AutoShowHide {
   
     final List attribute_names = ["message", "autohide_delay", "permanent", "container_selector", "message_type", "ignore_duplicates"];
           List native_events   = ["close.click"];
           Map default_attribute_values = {
             "container_name": "#simple_notifications_container",
  -          "permanent": false,
  -          "autohide_delay": 10,
  -          "message_type": "neutral",
  -          "ignore_duplicates": true
  +          "permanent": false,   // will not allow this notification to be closed
  +          "autohide_delay": 10, // will hide the notification
  +          "message_type": "neutral", // adds css class "message-type-neutral"
  +          "ignore_duplicates": true  // if set to false, allows duplicate notifications to be displayed in the same container
           };
   
     Future autohide_future;
  
positive.code:     autohide();
    }
  
    void hide() {
      if(this.permanent == null || this.permanent == false) {
        behave("hide");
  
negative.code:     this.show();
    }
  
    /** Before actually displaying the notification, this method checks whether there are duplicates
      * of the notification in the specified container. It also launches autohide() if applicable.
      */
    void show() {
  
      // Don't do anything if a similar message has been displayed before.
  