Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.810
diff -u -r1.810 system.module
--- modules/system/system.module	13 Oct 2009 21:34:15 -0000	1.810
+++ modules/system/system.module	13 Oct 2009 23:42:57 -0000
@@ -463,6 +463,12 @@
     '#default_tab' => '',
     '#process' => array('form_process_vertical_tabs'),
   );
+
+  $types['container'] = array(
+    '#theme_wrappers' => array('container'),
+    '#process' => array('form_process_container'),
+  );
+
   $types['token'] = array(
     '#input' => TRUE,
     '#theme' => array('hidden'),
Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.212
diff -u -r1.212 system.admin.inc
--- modules/system/system.admin.inc	13 Oct 2009 21:34:15 -0000	1.212
+++ modules/system/system.admin.inc	13 Oct 2009 23:42:57 -0000
@@ -495,17 +495,26 @@
       '#tree' => FALSE,
       '#description' => t('Check here if you want the theme to use the logo supplied with it.')
     );
-    $form['logo']['logo_path'] = array(
+    $form['logo']['logo_settings'] = array(
+      '#type' => 'container',
+      '#states' => array(
+        // Hide the logo settings when using the default logo.
+        'invisible' => array(
+          'input[name="default_logo"]' => array('checked' => TRUE),
+        ),
+      ),
+    );
+    $form['logo']['logo_settings']['logo_path'] = array(
       '#type' => 'textfield',
       '#title' => t('Path to custom logo'),
       '#default_value' => $settings['logo_path'],
-      '#description' => t('The path to the file you would like to use as your logo file instead of the default logo.'));
-
-    $form['logo']['logo_upload'] = array(
+      '#description' => t('The path to the file you would like to use as your logo file instead of the default logo.'),
+    );
+    $form['logo']['logo_settings']['logo_upload'] = array(
       '#type' => 'file',
       '#title' => t('Upload logo image'),
       '#maxlength' => 40,
-      '#description' => t("If you don't have direct file access to the server, use this field to upload your logo.")
+      '#description' => t("If you don't have direct file access to the server, use this field to upload your logo."),
     );
   }
 
@@ -521,17 +530,25 @@
       '#default_value' => $settings['default_favicon'],
       '#description' => t('Check here if you want the theme to use the default shortcut icon.')
     );
-    $form['favicon']['favicon_path'] = array(
+    $form['favicon']['favicon_settings'] = array(
+      '#type' => 'container',
+      '#states' => array(
+        // Hide the favicon settings when using the default favicon.
+        'invisible' => array(
+          'input[name="default_favicon"]' => array('checked' => TRUE),
+        ),
+      ),
+    );
+    $form['favicon']['favicon_settings']['favicon_path'] = array(
       '#type' => 'textfield',
       '#title' => t('Path to custom icon'),
       '#default_value' => $settings['favicon_path'],
-      '#description' => t('The path to the image file you would like to use as your custom shortcut icon.')
+      '#description' => t('The path to the image file you would like to use as your custom shortcut icon.'),
     );
-
-    $form['favicon']['favicon_upload'] = array(
+    $form['favicon']['favicon_settings']['favicon_upload'] = array(
       '#type' => 'file',
       '#title' => t('Upload icon image'),
-      '#description' => t("If you don't have direct file access to the server, use this field to upload your shortcut icon.")
+      '#description' => t("If you don't have direct file access to the server, use this field to upload your shortcut icon."),
     );
   }
 
@@ -1646,12 +1663,16 @@
     '#default_value' => $configurable_timezones,
   );
 
-  $js_hide = !$configurable_timezones ? ' class="js-hide"' : '';
   $form['timezone']['configurable_timezones_wrapper'] =  array(
-    '#prefix' => '<div id="empty-timezone-message-wrapper"' . $js_hide . '>',
-    '#suffix' => '</div>',
+    '#type' => 'container',
+    '#states' => array(
+      // Hide the user configured timezone settings when users are forced to use
+      // the default setting.
+      'invisible' => array(
+        'input[name="configurable_timezones"]' => array('checked' => FALSE),
+      ),
+    ),
   );
-
   $form['timezone']['configurable_timezones_wrapper']['empty_timezone_message'] = array(
     '#type' => 'checkbox',
     '#title' => t('Remind users at login if their time zone is not set.'),
Index: modules/system/system.js
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.js,v
retrieving revision 1.36
diff -u -r1.36 system.js
--- modules/system/system.js	13 Oct 2009 21:34:15 -0000	1.36
+++ modules/system/system.js	13 Oct 2009 23:42:57 -0000
@@ -115,19 +115,6 @@
 };
 
 /**
- * Show/hide settings for user configurable time zones depending on whether
- * users are able to set their own time zones or not.
- */
-Drupal.behaviors.userTimeZones = {
-  attach: function (context, settings) {
-    $('#empty-timezone-message-wrapper .description').hide();
-    $('#edit-configurable-timezones', context).change(function () {
-      $('#empty-timezone-message-wrapper').toggle();
-    });
-  }
-};
-
-/**
  * Show the powered by Drupal image preview
  */
 Drupal.behaviors.poweredByPreview = {
Index: modules/node/node.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.pages.inc,v
retrieving revision 1.87
diff -u -r1.87 node.pages.inc
--- modules/node/node.pages.inc	11 Oct 2009 03:07:18 -0000	1.87
+++ modules/node/node.pages.inc	13 Oct 2009 23:42:57 -0000
@@ -178,6 +178,12 @@
       '#type' => 'checkbox',
       '#title' => t('Create new revision'),
       '#default_value' => $node->revision,
+      '#states' => array(
+        // Check the revision log checkbox when the log textarea is filled in.
+        'checked' => array(
+          'textarea[name="log"]' => array('empty' => FALSE),
+        ),
+      ),
     );
     $form['revision_information']['log'] = array(
       '#type' => 'textarea',
Index: modules/user/user.js
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.js,v
retrieving revision 1.18
diff -u -r1.18 user.js
--- modules/user/user.js	21 Sep 2009 08:52:41 -0000	1.18
+++ modules/user/user.js	13 Oct 2009 23:42:57 -0000
@@ -176,16 +176,4 @@
 
 };
 
-/**
- * Show all of the picture-related form elements at admin/config/people/accounts
- * depending on whether user pictures are enabled or not.
- */
-Drupal.behaviors.userSettings = {
-  attach: function (context, settings) {
-    $('#edit-user-pictures', context).change(function () {
-      $('div.user-admin-picture-settings', context).toggle();
-    });
-  }
-};
-
 })(jQuery);
Index: modules/user/user.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.admin.inc,v
retrieving revision 1.84
diff -u -r1.84 user.admin.inc
--- modules/user/user.admin.inc	10 Oct 2009 16:48:39 -0000	1.84
+++ modules/user/user.admin.inc	13 Oct 2009 23:42:57 -0000
@@ -342,15 +342,14 @@
     '#default_value' => $picture_support,
   );
   drupal_add_js(drupal_get_path('module', 'user') . '/user.js');
-  // If JS is enabled, and the checkbox defaults to off, hide all the settings
-  // on page load via CSS using the js-hide class so there's no flicker.
-  $css_class = 'user-admin-picture-settings';
-  if (!$picture_support) {
-    $css_class .= ' js-hide';
-  }
   $form['personalization']['pictures'] = array(
-    '#prefix' => '<div class="' . $css_class . '">',
-    '#suffix' => '</div>',
+    '#type' => 'container',
+    '#states' => array(
+      // Hide the additional picture settings when user pictures are disabled.
+      'invisible' => array(
+        'input[name="user_pictures"]' => array('checked' => FALSE),
+      ),
+    ),
   );
   $form['personalization']['pictures']['user_picture_path'] = array(
     '#type' => 'textfield',
@@ -511,13 +510,22 @@
     '#title' => t('Notify user when account is activated.'),
     '#default_value' => variable_get('user_mail_status_activated_notify', TRUE),
   );
-  $form['email_activated']['user_mail_status_activated_subject'] = array(
+  $form['email_activated']['settings'] = array(
+    '#type' => 'container',
+    '#states' => array(
+      // Hide the additional settings when this email is disabled.
+      'invisible' => array(
+        'input[name="user_mail_status_activated_notify"]' => array('checked' => FALSE),
+      ),
+    ),
+  );
+  $form['email_activated']['settings']['user_mail_status_activated_subject'] = array(
     '#type' => 'textfield',
     '#title' => t('Subject'),
     '#default_value' => _user_mail_text('status_activated_subject'),
     '#maxlength' => 180,
   );
-  $form['email_activated']['user_mail_status_activated_body'] = array(
+  $form['email_activated']['settings']['user_mail_status_activated_body'] = array(
     '#type' => 'textarea',
     '#title' => t('Body'),
     '#default_value' => _user_mail_text('status_activated_body'),
@@ -537,13 +545,22 @@
     '#title' => t('Notify user when account is blocked.'),
     '#default_value' => variable_get('user_mail_status_blocked_notify', FALSE),
   );
-  $form['email_blocked']['user_mail_status_blocked_subject'] = array(
+  $form['email_blocked']['settings'] = array(
+    '#type' => 'container',
+    '#states' => array(
+      // Hide the additional settings when the blocked email is disabled.
+      'invisible' => array(
+        'input[name="user_mail_status_blocked_notify"]' => array('checked' => FALSE),
+      ),
+    ),
+  );
+  $form['email_blocked']['settings']['user_mail_status_blocked_subject'] = array(
     '#type' => 'textfield',
     '#title' => t('Subject'),
     '#default_value' => _user_mail_text('status_blocked_subject'),
     '#maxlength' => 180,
   );
-  $form['email_blocked']['user_mail_status_blocked_body'] = array(
+  $form['email_blocked']['settings']['user_mail_status_blocked_body'] = array(
     '#type' => 'textarea',
     '#title' => t('Body'),
     '#default_value' => _user_mail_text('status_blocked_body'),
@@ -584,13 +601,22 @@
     '#title' => t('Notify user when account is canceled.'),
     '#default_value' => variable_get('user_mail_status_canceled_notify', FALSE),
   );
-  $form['email_canceled']['user_mail_status_canceled_subject'] = array(
+  $form['email_canceled']['settings'] = array(
+    '#type' => 'container',
+    '#states' => array(
+      // Hide the settings when the cancel notify checkbox is disabled. 
+      'invisible' => array(
+        'input[name="user_mail_status_canceled_notify"]' => array('checked' => FALSE),
+      ),
+    ),
+  );
+  $form['email_canceled']['settings']['user_mail_status_canceled_subject'] = array(
     '#type' => 'textfield',
     '#title' => t('Subject'),
     '#default_value' => _user_mail_text('status_canceled_subject'),
     '#maxlength' => 180,
   );
-  $form['email_canceled']['user_mail_status_canceled_body'] = array(
+  $form['email_canceled']['settings']['user_mail_status_canceled_body'] = array(
     '#type' => 'textarea',
     '#title' => t('Body'),
     '#default_value' => _user_mail_text('status_canceled_body'),
Index: misc/collapse.js
===================================================================
RCS file: /cvs/drupal/drupal/misc/collapse.js,v
retrieving revision 1.25
diff -u -r1.25 collapse.js
--- misc/collapse.js	11 Sep 2009 02:01:26 -0000	1.25
+++ misc/collapse.js	13 Oct 2009 23:42:57 -0000
@@ -9,7 +9,9 @@
     // Action div containers are processed separately because of a IE bug
     // that alters the default submit button behavior.
     var content = $('> div:not(.action)', fieldset);
-    $(fieldset).removeClass('collapsed');
+    $(fieldset)
+      .removeClass('collapsed')
+      .trigger({ type: 'collapsed', value: false });
     content.hide();
     content.slideDown({
       duration: 'fast',
@@ -27,6 +29,7 @@
   }
   else {
     $('div.action', fieldset).hide();
+    $(fieldset).trigger({ type: 'collapsed', value: true });
     var content = $('> div:not(.action)', fieldset).slideUp('fast', function () {
       $(this.parentNode).addClass('collapsed');
       this.parentNode.animating = false;
Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1017
diff -u -r1.1017 common.inc
--- includes/common.inc	13 Oct 2009 21:16:42 -0000	1.1017
+++ includes/common.inc	13 Oct 2009 23:42:57 -0000
@@ -4508,6 +4508,12 @@
   // attached data associated with this element.
   drupal_process_attached($elements);
 
+  // Add the dependency information for this form element.
+  if (!empty($elements['#states'])) {
+    drupal_add_js('misc/states.js', array('weight' => JS_LIBRARY + 1));
+    drupal_add_js(array('states' => array('#' . $elements['#id'] => $elements['#states'])), 'setting');
+  }
+
   $prefix = isset($elements['#prefix']) ? $elements['#prefix'] : '';
   $suffix = isset($elements['#suffix']) ? $elements['#suffix'] : '';
 
@@ -5022,6 +5028,9 @@
     'vertical_tabs' => array(
       'arguments' => array('element' => NULL),
     ),
+    'container' => array(
+      'arguments' => array('element' => NULL),
+    ),
   );
 }
 
Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.383
diff -u -r1.383 form.inc
--- includes/form.inc	13 Oct 2009 16:38:42 -0000	1.383
+++ includes/form.inc	13 Oct 2009 23:42:57 -0000
@@ -2133,6 +2133,39 @@
 }
 
 /**
+ * Processes a container element.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   container.
+ * @param $form_state
+ *   The $form_state array for the form this element belongs to.
+ * @return
+ *   The processed element.
+ */
+function form_process_container($element, &$form_state) {
+  $element['#id'] = drupal_html_id(implode('-', $element['#parents']) . '-wrapper');
+  return $element;
+}
+
+/**
+ * Adds a container for grouped items
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   group.
+ *   Properties used: #children.
+ * @return
+ *   A themed HTML string representing the form element.
+ *
+ * @ingroup themeable
+ */
+function theme_container($variables) {
+  $element = $variables['element'];
+  return '<div class="form-wrapper" id="' . $element['#id'] . '">' . $element['#children'] . '</div>';
+}
+
+/**
  * Format a table with radio buttons or checkboxes.
  *
  * @param $variables
Index: misc/states.js
===================================================================
RCS file: misc/states.js
diff -N misc/states.js
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ misc/states.js	1 Jan 1970 00:00:00 -0000
@@ -0,0 +1,396 @@
+// $Id$
+(function ($) {
+
+/**
+ * The base States namespace.
+ *
+ * Having the local states variable allows us to use the States namespace
+ * without having to always declare "Drupal.states".
+ */
+var states = Drupal.states = {
+  // An array of functions that should be postponed.
+  postponed: []
+};
+
+/**
+ * Attaches the states.
+ */
+Drupal.behaviors.states = {
+  attach: function (context, settings) {
+    for (var selector in settings.states) {
+      for (var state in settings.states[selector]) {
+        new states.Dependant({
+          element: $(selector),
+          state: states.State.sanitize(state),
+          dependees: settings.states[selector][state]
+        });
+      }
+    }
+
+    // Execute all postponed functions now.
+    while (states.postponed.length) {
+      (states.postponed.shift())();
+    }
+  }
+};
+
+/**
+ * An object representing a an element that depends on other elements.
+ *
+ * @param args
+ *   An object with the following keys (all of which are required):
+ *   - element: A jQuery object of the dependant element
+ *   - state: A State object describing the state that is dependant
+ *   - dependees: An object with dependency specifications. Lists all elements
+ *     that this element depends on.
+ */
+states.Dependant = function (args) {
+  $.extend(this, { values: {}, oldValue: undefined }, args);
+
+  for (var selector in this.dependees) {
+    this.initializeDependee(selector, this.dependees[selector]);
+  }
+};
+
+/**
+ * Comparison functions for comparing the value of an element with the
+ * specification from the dependency settings. If the object type can't be
+ * found in this list, the === operator is used by default.
+ */
+states.Dependant.comparisons = {
+  'RegExp': function (reference, value) {
+    return reference.test(value);
+  },
+  'Function': function (reference, value) {
+    // The "reference" variable is a comparison function.
+    return reference(value);
+  }
+};
+
+states.Dependant.prototype = {
+  /**
+   * Initializes one of the elements this dependant depends on.
+   *
+   * @param selector
+   *   The CSS selector describing the dependee.
+   * @param dependeeStates
+   *   The list of states that have to be monitored for tracking the
+   *   dependee's compliance status.
+   */
+  initializeDependee: function (selector, dependeeStates) {
+    var self = this;
+
+    // Cache for the states of this dependee.
+    self.values[selector] = {};
+
+    $.each(dependeeStates, function (state, value) {
+      state = states.State.sanitize(state);
+
+      // Initialize the value of this state.
+      self.values[selector][state.pristine] = undefined;
+
+      // Monitor state changes of the specified state for this dependee.
+      $(selector).bind('state:' + state, function (e) {
+        var complies = self.compare(value, e.value);
+        self.update(selector, state, complies);
+      });
+
+      // Make sure the event we just bound ourselves to is actually fired.
+      new states.Trigger({ selector: selector, state: state });
+    });
+  },
+
+  /**
+   * Compares a value with a reference value.
+   *
+   * @param reference
+   *   The value used for reference.
+   * @param value
+   *   The value to compare with the reference value.
+   * @return
+   *   true, undefined or false.
+   */
+  compare: function (reference, value) {
+    if (reference.constructor.name in states.Dependant.comparisons) {
+      // Use a custom compare function for certain reference value types.
+      return states.Dependant.comparisons[reference.constructor.name](reference, value);
+    }
+    else {
+      // Do a plain comparison otherwise.
+      return compare(reference, value);
+    }
+  },
+
+  /**
+   * Update the value of a dependee's state.
+   *
+   * @param selector
+   *   CSS selector describing the dependee.
+   * @param state
+   *   A State object describing the dependee's updated state.
+   * @param value
+   *   The new value for the dependee's updated state.
+   */
+  update: function (selector, state, value) {
+    // Only act when the 'new' value is actually new.
+    if (value !== this.values[selector][state.pristine]) {
+      this.values[selector][state.pristine] = value;
+      this.reevaluate();
+    }
+  },
+
+  /**
+   * Triggers change events in case a state changed.
+   */
+  reevaluate: function () {
+    var value = undefined;
+
+    // Merge all individual values to find out whether this dependee complies.
+    for (var selector in this.values) {
+      for (var state in this.values[selector]) {
+        state = states.State.sanitize(state);
+        var complies = this.values[selector][state.pristine];
+        value = ternary(value, invert(complies, state.invert));
+      }
+    }
+
+    // Only invoke a state change event when the value actually changed.
+    if (value !== this.oldValue) {
+      // Store the new value so that we can compare later whether the value
+      // actually changed.
+      this.oldValue = value;
+
+      // Normalize the value to match the normalized state name.
+      value = invert(value, this.state.invert);
+
+      // By adding "trigger: true", we ensure that state changes don't go into
+      // infinite loops.
+      this.element.trigger({ type: 'state:' + this.state, value: value, trigger: true });
+    }
+  }
+};
+
+states.Trigger = function (args) {
+  $.extend(this, args);
+
+  if (this.state in states.Trigger.states) {
+    this.element = $(this.selector);
+
+    // Only call the trigger initializer when it wasn't yet attached to this
+    // element. Otherwise we'd end up with duplicate events.
+    if (!this.element.data('trigger:' + this.state)) {
+      this.initialize();
+    }
+  }
+};
+
+states.Trigger.prototype = {
+  initialize: function () {
+    var self = this;
+    var trigger = states.Trigger.states[this.state];
+
+    if (typeof trigger == 'function') {
+      // We have a custom trigger initialization function.
+      trigger.call(window, this.element);
+    }
+    else {
+      $.each(trigger, function (event, valueFn) {
+        self.defaultTrigger(event, valueFn);
+      });
+    }
+
+    // Mark this trigger as initialized for this element.
+    this.element.data('trigger:' + this.state, true);
+  },
+
+  defaultTrigger: function (event, valueFn) {
+    var self = this;
+    var oldValue = valueFn.call(this.element);
+
+    // Attach the event callback.
+    this.element.bind(event, function (e) {
+      var value = valueFn.call(self.element, e);
+      // Only trigger the event if the value has actually changed.
+      if (oldValue !== value) {
+        self.element.trigger({ type: 'state:' + self.state, value: value, oldValue: oldValue });
+        oldValue = value;
+      }
+    });
+
+    states.postponed.push(function () {
+      // Trigger the event once for initialization purposes.
+      self.element.trigger({ type: 'state:' + self.state, value: oldValue, oldValue: undefined });
+    });
+  }
+};
+
+/**
+ * This list of states contains functions that are used to monitor the state
+ * of an element. Whenever an element depends on the state of another element,
+ * one of these trigger functions is added to the dependee so that the
+ * dependant element can be updated.
+ */
+states.Trigger.states = {
+  // 'empty' describes the state to be monitored
+  empty: {
+    // 'keyup' is the (native DOM) event that we watch for.
+    'keyup': function () {
+      // The function associated to that trigger returns the new value for the
+      // state.
+      return this.val() == '';
+    }
+  },
+
+  checked: {
+    'change': function () {
+      return this.attr('checked');
+    }
+  },
+
+  value: {
+    'keyup': function () {
+      return this.val();
+    }
+  },
+
+  collapsed: {
+    'collapsed': function(e) {
+      return (e !== undefined && 'value' in e) ? e.value : this.is('.collapsed');
+    }
+  }
+};
+
+
+/**
+ * A state object is used for describing the state and performing aliasing.
+ */
+states.State = function(state) {
+  // We may need the original unresolved name later.
+  this.pristine = this.name = state;
+
+  // Normalize the state name.
+  while(true) {
+    // Iteratively remove exclamation marks and invert the value.
+    while (this.name.charAt(0) == '!') {
+      this.name = this.name.substring(1);
+      this.invert = !this.invert;
+    }
+
+    // Replace the state with its normalized name.
+    if (this.name in states.State.aliases)
+      this.name = states.State.aliases[this.name];
+    else
+      break;
+  }
+};
+
+/**
+ * Create a new State object by sanitizing the passed value.
+ */
+states.State.sanitize = function (state) {
+  if (state instanceof states.State) {
+    return state;
+  }
+  else {
+    return new states.State(state);
+  }
+};
+
+/**
+ * This list of aliases is used to normalize states and associates negated names
+ * with their respective inverse state.
+ */
+states.State.aliases = {
+  'enabled': '!disabled',
+  'invisible': '!visible',
+  'invalid': '!valid',
+  'untouched': '!touched',
+  'optional': '!required',
+  'filled': '!empty',
+  'unchecked': '!checked',
+  'irrelevant': '!relevant',
+  'expanded': '!collapsed',
+  'readwrite': '!readonly'
+};
+
+states.State.prototype = {
+  invert: false,
+
+  /**
+   * Ensures that just using the state object returns the name.
+   */
+  toString: function() {
+    return this.name;
+  }
+};
+
+/**
+ * Global state change handlers. These are bound to "document" to cover all
+ * elements whose state changes. Events sent to elements within the page
+ * bubble up to these handlers. We use this system so that themes and modules
+ * can override these state change handlers for particular parts of a page.
+ */
+{
+  $(document).bind('state:disabled', function(e) {
+    // Only act when this change was triggered by a dependency and not by the
+    // element monitoring itself.
+    if (e.trigger) {
+      $(e.target)
+        .attr('disabled', e.value)
+        .filter('.form-element')
+          .closest('.form-item, .form-wrapper')[e.value ? 'addClass' : 'removeClass']('form-disabled');
+
+      // Note: WebKit nightlies don't reflect that change correctly.
+      // See https://bugs.webkit.org/show_bug.cgi?id=23789
+    }
+  });
+
+  $(document).bind('state:required', function(e) {
+    if (e.trigger) {
+      $(e.target).closest('.form-item, .form-wrapper')[e.value ? 'addClass' : 'removeClass']('form-required');
+    }
+  });
+
+  $(document).bind('state:visible', function(e) {
+    if (e.trigger) {
+      $(e.target).closest('.form-item, .form-wrapper')[e.value ? 'show' : 'hide']();
+    }
+  });
+
+  $(document).bind('state:checked', function(e) {
+    if (e.trigger) {
+      $(e.target).attr('checked', e.value);
+    }
+  });
+
+  $(document).bind('state:collapsed', function(e) {
+    if (e.trigger) {
+      if ($(e.target).is('.collapsed') !== e.value) {
+        $('> legend a', e.target).click();
+      }
+    }
+  });
+}
+
+/**
+ * These are helper functions implementing addition "operators" and don't
+ * implement any logic that is particular to states.
+ */
+{
+  // Bitwise AND with a third undefined state.
+  function ternary (a, b) {
+    return a === undefined ? b : (b === undefined ? a : a && b);
+  };
+
+  // Inverts a (if it's not undefined) when invert is true.
+  function invert (a, invert) {
+    return (invert && a !== undefined) ? !a : a;
+  };
+
+  // Compares two values while ignoring undefined values.
+  function compare (a, b) {
+    return (a === b) ? (a === undefined ? a : true) : (a === undefined || b === undefined);
+  }
+}
+
+})(jQuery);