Is there an ready-made solution to mark edited form fields? When you edit something in text editor or IDE, you get visual feedback - star next to file name, bolded file name et cetera. That way you easily know what has been edited and what not.

Is there a ready made solution to introduce that to Drupal? Either system-wide or manually using Form API? It would make sense to see if any changes was made or not, especially if one opens dozen of nodes for updates and then sees some of them are already up to date and does not need a save (and associated boost cache clears).

In large setting forms, like permissions or Elysia Cron, it would help too.

The ideal would be to add some class to each field with value not equal it's default value, so the theme could deal with it using only CSS.

Anyone written it already?
I've only seen Track Field Changes, but that doesn't give immediate visual feedback.

Edit: I know you asked for something that was already out in the wild, but the following might be useful.

I guess you could write something custom relatively easily though using jQuery's .change event.

Something like the following I guess (code will need checking but it should be pretty near).

JavaScript

(function ($) {
    Drupal.behaviors.formFieldTracker = {
      attach: function(){
        $(input).change(function(){
          $(this).addClass('field-edited');
        }));
      }
    }
})(jQuery)


Module

function MYMODULE_preprocess_page(&amp;$vars) {
  // Only add the JavaScript on admin pages as defined by hook_admin_paths()
  if (path_is_admin(current_path())) {
    $path = drupal_get_path('module', 'MYMODULE');
    drupal_add_js($path . '/js/MYSCRIPT.js');
    $vars['scripts'] = drupal_get_js();
  }
}


Then you could add whatever CSS you fancy afterwards:

.field-edited:after {
  content: 'Edited';
  display: inline-block;
  color: #F00;
  font-style: italic;
}