Index: includes/ajax.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/ajax.inc,v
retrieving revision 1.25
diff -u -p -r1.25 ajax.inc
--- includes/ajax.inc	27 Jan 2010 11:19:11 -0000	1.25
+++ includes/ajax.inc	30 Jan 2010 18:58:56 -0000
@@ -293,28 +293,12 @@ function ajax_get_form() {
  * The Form API #ajax property can be set both for buttons and other input
  * elements.
  *
- * ajax_process_form() defines an additional 'formPath' JavaScript setting
- * that is used by Drupal.ajax.prototype.beforeSubmit() to automatically inject
- * an additional field 'ajax_triggering_element' to the submitted form values,
- * which contains the array #parents of the element in the form structure.
- * This additional field allows ajax_form_callback() to determine which
- * element triggered the action, as non-submit form elements do not
- * provide this information in $form_state['clicked_button'], which can
- * also be used to determine triggering element, but only submit-type
- * form elements.
- *
  * This function is also the canonical example of how to implement
  * #ajax['path']. If processing is required that cannot be accomplished with
  * a callback, re-implement this function and set #ajax['path'] to the
  * enhanced function.
  */
 function ajax_form_callback() {
-  // Find the triggering element, which was set up for us on the client side.
-  if (!empty($_REQUEST['ajax_triggering_element'])) {
-    $triggering_element_path = $_REQUEST['ajax_triggering_element'];
-    // Remove the value for form validation.
-    unset($_REQUEST['ajax_triggering_element']);
-  }
   list($form, $form_state, $form_id, $form_build_id) = ajax_get_form();
 
   // Build, validate and if possible, submit the form.
@@ -324,32 +308,11 @@ function ajax_form_callback() {
   // drupal_process_form() set up.
   $form = drupal_rebuild_form($form_id, $form_state, $form_build_id);
 
-  // $triggering_element_path in a simple form might just be 'myselect', which
-  // would mean we should use the element $form['myselect']. For nested form
-  // elements we need to recurse into the form structure to find the triggering
-  // element, so we can retrieve the #ajax['callback'] from it.
-  if (!empty($triggering_element_path)) {
-    if (!isset($form['#access']) || $form['#access']) {
-      $triggering_element = $form;
-      foreach (explode('/', $triggering_element_path) as $key) {
-        if (!empty($triggering_element[$key]) && (!isset($triggering_element[$key]['#access']) || $triggering_element[$key]['#access'])) {
-          $triggering_element = $triggering_element[$key];
-        }
-        else {
-          // We did not find the $triggering_element or do not have #access,
-          // so break out and do not provide it.
-          $triggering_element = NULL;
-          break;
-        }
-      }
-    }
-  }
-  if (empty($triggering_element)) {
-    $triggering_element = $form_state['clicked_button'];
-  }
-  // Now that we have the element, get a callback if there is one.
-  if (!empty($triggering_element)) {
-    $callback = $triggering_element['#ajax']['callback'];
+  // As part of drupal_process_form(), the element that triggered the form
+  // submission is determined, and in the case of AJAX, it might not be a
+  // button. This lets us route to the appropriate callback.
+  if (!empty($form_state['triggering_element'])) {
+    $callback = $form_state['triggering_element']['#ajax']['callback'];
   }
   if (!empty($callback) && function_exists($callback)) {
     return $callback($form, $form_state);
@@ -483,13 +446,43 @@ function ajax_process_form($element, &$f
       'speed' => 'none',
       'method' => 'replace',
       'progress' => array('type' => 'throbber'),
-      'formPath' => implode('/', $element['#array_parents']),
     );
 
-    // Process special settings.
+    // Change path to url.
     $settings['url'] = isset($settings['path']) ? url($settings['path']) : url('system/ajax');
     unset($settings['path']);
-    $settings['button'] = isset($element['#executes_submit_callback']) ? array($element['#name'] => $element['#value']) : FALSE;
+
+    // Add special data to $settings['submit'] so that when this element
+    // triggers an AJAX submission, Drupal's form processing can determine which
+    // element triggered it.
+    if (isset($settings['trigger_as'])) {
+      // An element can add a 'trigger_as' key within #ajax to make the element
+      // submit as though another one (for example, a non-button can use this
+      // to submit the form as though a button were clicked). To emulate a
+      // button, this should be set to an array with the button name as the key
+      // and the button value as the value. To emulate a non-button or image
+      // button, this should be set to just the element's name.
+      if (is_array($settings['trigger_as'])) {
+        // Use the first key/value pair in the array.
+        $settings['submit']['_triggering_element_value'] = reset($settings['trigger_as']);
+        $settings['submit']['_triggering_element_name'] = key($settings['trigger_as']);
+      }
+      else {
+        $settings['submit']['_triggering_element_name'] = $settings['trigger_as'];
+      }
+    }
+    else {
+      // Most of the time, elements can submit as themselves, in which case the
+      // 'trigger_as' key isn't needed, and the element's name is used.
+      $settings['submit']['_triggering_element_name'] = $element['#name'];
+      // If the element is a (non-image) button, its name may not identify it
+      // uniquely, in which case a match on value is also needed.
+      // @see _form_button_was_clicked()
+      if (isset($element['#button_type']) && empty($element['#has_garbage_value'])) {
+        $settings['submit']['_triggering_element_value'] = $element['#value'];
+      }
+    }
+    unset($settings['trigger_as']);
 
     // Convert a simple #ajax['progress'] string into an array.
     if (is_string($settings['progress'])) {
Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.428
diff -u -p -r1.428 form.inc
--- includes/form.inc	30 Jan 2010 07:54:01 -0000	1.428
+++ includes/form.inc	30 Jan 2010 18:58:56 -0000
@@ -280,19 +280,21 @@ function form_state_defaults() {
     'cache'=> FALSE,
     'method' => 'post',
     'groups' => array(),
+    'buttons' => array(),
   );
 }
 
 /**
  * Retrieves a form, caches it and processes it again.
  *
- * If your AHAH callback simulates the pressing of a button, then your AHAH
- * callback will need to do the same as what drupal_get_form would do when the
+ * If your AJAX callback simulates the pressing of a button, then your AJAX
+ * callback will need to do the same as what drupal_get_form() would do when the
  * button is pressed: get the form from the cache, run drupal_process_form over
- * it and then if it needs rebuild, run drupal_rebuild_form over it. Then send
+ * it and then if it needs rebuild, run drupal_rebuild_form() over it. Then send
  * back a part of the returned form.
- * $form_state['clicked_button']['#array_parents'] will help you to find which
- * part.
+ * $form_state['triggering_element']['#array_parents'] will help you to find
+ * which part.
+ * @see ajax_form_callback() for an example.
  *
  * @param $form_id
  *   The unique string identifying the desired form. If a function
@@ -405,6 +407,7 @@ function form_state_keys_no_cache() {
     'temporary',
     // Internal properties defined by form processing.
     'buttons',
+    'triggering_element',
     'clicked_button',
     'complete form',
     'groups',
@@ -936,22 +939,35 @@ function _form_validate(&$elements, &$fo
     // to form_set_error() be suppressed and not result in a form error, so
     // that a button that implements low-risk functionality (such as "Previous"
     // or "Add more") that doesn't require all user input to be valid can still
-    // have its submit handlers triggered. The clicked button's
+    // have its submit handlers triggered. The triggering element's
     // #limit_validation_errors property contains the information for which
     // errors are needed, and all other errors are to be suppressed. The
-    // #limit_validation_errors property is ignored if the button doesn't also
-    // define its own submit handlers, because it's too large a security risk to
-    // have any invalid user input when executing form-level submit handlers.
-    if (isset($form_state['clicked_button']['#limit_validation_errors']) && isset($form_state['clicked_button']['#submit'])) {
-      form_set_error(NULL, '', $form_state['clicked_button']['#limit_validation_errors']);
-    }
+    // #limit_validation_errors property is ignored if submit handlers will run,
+    // but the element doesn't have a #submit property, because it's too large a
+    // security risk to have any invalid user input when executing form-level
+    // submit handlers.
+    if (isset($form_state['triggering_element']['#limit_validation_errors']) && ($form_state['triggering_element']['#limit_validation_errors'] !== FALSE) && !($form_state['submitted'] && !isset($form_state['triggering_element']['#submit']))) {
+      form_set_error(NULL, '', $form_state['triggering_element']['#limit_validation_errors']);
+    }
+    // If submit handlers won't run (due to the submission having been triggered
+    // by an element whose #executes_submit_callback property isn't TRUE), then
+    // it's safe to suppress all validation errors, and we do so by default,
+    // which is particularly useful during an AJAX submission triggered by a
+    // non-button. An element can override this default by setting the
+    // #limit_validation_errors property. For button element types,
+    // #limit_validation_errors defaults to FALSE (via system_element_info()),
+    // so that full validation is their default behavior.
+    elseif (isset($form_state['triggering_element']) && !isset($form_state['triggering_element']['#limit_validation_errors']) && !$form_state['submitted']) {
+      form_set_error(NULL, '', array());
+    }
+    // As an extra security measure, explicitly turn off error suppression if
+    // one of the above conditions wasn't met. Since this is also done at the
+    // end of this function, doing it here is only to handle the rare edge case
+    // where a validate handler invokes form processing of another form.
     else {
-      // As an extra security measure, explicitly turn off error suppression.
-      // Since this is also done at the end of this function, doing it here is
-      // only to handle the rare edge case where a validate handler invokes form
-      // processing of another form.
       drupal_static_reset('form_set_error:limit_validation_errors');
     }
+
     // Make sure a value is passed when the field is required.
     // A simple call to empty() will not cut it here as some fields, like
     // checkboxes, can return a valid value of '0'. Instead, check the
@@ -1303,22 +1319,60 @@ function form_builder($form_id, $element
     $element['#after_build_done'] = TRUE;
   }
 
-  // Now that we've processed everything, we can go back to handle the funky
-  // Internet Explorer button-click scenario.
-  _form_builder_ie_cleanup($element, $form_state);
-
   // If there is a file element, we need to flip a flag so later the
   // form encoding can be set.
   if (isset($element['#type']) && $element['#type'] == 'file') {
     $form_state['has_file_element'] = TRUE;
   }
 
+  // Final tasks for the form element after form_builder() has run for all other
+  // elements.
   if (isset($element['#type']) && $element['#type'] == 'form') {
-    // We are on the top form.
     // If there is a file element, we set the form encoding.
     if (isset($form_state['has_file_element'])) {
       $element['#attributes']['enctype'] = 'multipart/form-data';
     }
+
+    // Now that we've processed everything, we can go back to handle the funky
+    // Internet Explorer button-click scenario.
+    _form_builder_ie_cleanup($element, $form_state);
+
+    // If the triggering element specifies "button-level" validation and submit
+    // handlers to run instead of the default form-level ones, then add those to
+    // the form state.
+    foreach (array('validate', 'submit') as $type) {
+      if (isset($form_state['triggering_element']['#' . $type])) {
+        $form_state[$type . '_handlers'] = $form_state['triggering_element']['#' . $type];
+      }
+    }
+
+    // If the triggering element executes submit handlers, then set the form
+    // state key that's needed for those handlers to run.
+    if (!empty($form_state['triggering_element']['#executes_submit_callback'])) {
+      $form_state['submitted'] = TRUE;
+    }
+
+    // Special processing if the triggering element is a button.
+    if (isset($form_state['triggering_element']['#button_type'])) {
+      // Because there are several ways in which the triggering element could
+      // have been determined (including from input variables set by JavaScript
+      // or fallback behavior implemented for IE), and because buttons often
+      // have their #name property not derived from their #parents property, we
+      // can't assume that input processing that's happened up until here has
+      // resulted in $form_state['values'][BUTTON_NAME] being set. But it's
+      // common for forms to have several buttons named 'op' and switch on
+      // $form_state['values']['op'] during submit handler execution.
+      $form_state['values'][$form_state['triggering_element']['#name']] = $form_state['triggering_element']['#value'];
+
+      // @todo To support AJAX form submissions from non-button elements,
+      //   the older Drupal variable $form_state['clicked_button'] got
+      //   abstracted to $form_state['triggering_element'], but this was done
+      //   after Drupal 7 alpha release. Until we're ready to break
+      //   compatibility with modules using $form_state['clicked_button'], we
+      //   continue to provide this variable.
+      $form_state['clicked_button'] = $form_state['triggering_element'];
+    }
+
     // Update the copy of the complete form for usage in validation handlers.
     $form_state['complete form'] = $element;
   }
@@ -1415,52 +1469,78 @@ function _form_builder_handle_input_elem
     }
   }
 
-  // Determine which button (if any) was clicked to submit the form.
-  // We compare the incoming values with the buttons defined in the form,
-  // and flag the one that matches. We have to do some funky tricks to
-  // deal with Internet Explorer's handling of single-button forms, though.
-  if (!empty($form_state['input']) && isset($element['#executes_submit_callback'])) {
-    // First, accumulate a collection of buttons, divided into two bins:
-    // those that execute full submit callbacks and those that only validate.
-    $button_type = $element['#executes_submit_callback'] ? 'submit' : 'button';
-    $form_state['buttons'][$button_type][] = $element;
-
-    if (_form_button_was_clicked($element, $form_state)) {
-      $form_state['submitted'] = $form_state['submitted'] || $element['#executes_submit_callback'];
-
-      // In most cases, we want to use form_set_value() to manipulate
-      // the global variables. In this special case, we want to make sure that
-      // the value of this element is listed in $form_variables under 'op'.
-      $form_state['values'][$element['#name']] = $element['#value'];
-      $form_state['clicked_button'] = $element;
-
-      if (isset($element['#validate'])) {
-        $form_state['validate_handlers'] = $element['#validate'];
+  // Determine which element (if any) triggered the submission of the form and
+  // keep track of all the buttons in the form for form_state_values_clean().
+  // @todo We need to add a #access check here, so that someone can't fake the
+  //   click of a button they shouldn't have access to, but first we need to
+  //   fix file.module's managed_file element pipeline to handle the click of
+  //   the remove button in a submit handler instead of in a #process function.
+  //   During the first run of form_builder() after the form is submitted,
+  //   #process functions need to return the expanded element with child
+  //   elements' #access properties matching what they were when the form was
+  //   displayed to the user, since that is what we are processing input for.
+  //   Changes to the form (like toggling the upload/remove button) need to wait
+  //   until form rebuild.
+  if (!empty($form_state['input'])) {
+    // Detect if the element triggered the submission via AJAX.
+    if (_form_element_triggered_scripted_submission($element, $form_state)) {
+      $form_state['triggering_element'] = $element;
+    }
+    // If the form was submitted by the browser rather than via AJAX, then it
+    // can only have been triggered by a button, and we need to determine which
+    // button within the constraints of how browsers provide this information.
+    if (isset($element['#button_type'])) {
+      // All buttons in the form need to be tracked both for
+      // form_state_values_clean() and for _form_builder_ie_cleanup().
+      // @todo When #access is checked in an outer if statement (see above), it
+      //   won't need to be checked here.
+      if ($form_state['programmed'] || !isset($element['#access']) || $element['#access']) {
+        $form_state['buttons'][] = $element;
       }
-      if (isset($element['#submit'])) {
-        $form_state['submit_handlers'] = $element['#submit'];
+      if (_form_button_was_clicked($element, $form_state)) {
+        $form_state['triggering_element'] = $element;
       }
     }
   }
+
   form_set_value($element, $element['#value'], $form_state);
 }
 
 /**
- * Helper function to handle the sometimes-convoluted logic of button
- * click detection.
+ * Helper function to handle the sometimes-convoluted logic of button click detection.
+ *
+ * This detects button or non-button controls that trigger a form submission via
+ * AJAX or some other scriptable environment. These environments can set the
+ * special input key '_triggering_element_name' to identify the triggering
+ * element. If the name alone doesn't identify the element uniquely, the input
+ * key '_triggering_element_value' may also be set to require a match on element
+ * value. An example where this is needed is if there are several buttons all
+ * named 'op', and only differing in their value.
+ */
+function _form_element_triggered_scripted_submission($element, &$form_state) {
+  if (!empty($form_state['input']['_triggering_element_name']) && $element['#name'] == $form_state['input']['_triggering_element_name']) {
+    if (empty($form_state['input']['_triggering_element_value']) || $form_state['input']['_triggering_element_value'] == $element['#value']) {
+      return TRUE;
+    }
+  }
+  return FALSE;
+}
+
+/**
+ * Helper function to handle the sometimes-convoluted logic of button click detection.
  *
  * In Internet Explorer, if ONLY one submit button is present, AND the
  * enter key is used to submit the form, no form value is sent for it
  * and we'll never detect a match. That special case is handled by
  * _form_builder_ie_cleanup().
  */
-function _form_button_was_clicked($form, &$form_state) {
+function _form_button_was_clicked($element, &$form_state) {
   // First detect normal 'vanilla' button clicks. Traditionally, all
   // standard buttons on a form share the same name (usually 'op'),
   // and the specific return value is used to determine which was
   // clicked. This ONLY works as long as $form['#name'] puts the
   // value at the top level of the tree of $_POST data.
-  if (isset($form_state['input'][$form['#name']]) && $form_state['input'][$form['#name']] == $form['#value']) {
+  if (isset($form_state['input'][$element['#name']]) && $form_state['input'][$element['#name']] == $element['#value']) {
     return TRUE;
   }
   // When image buttons are clicked, browsers do NOT pass the form element
@@ -1468,38 +1548,22 @@ function _form_button_was_clicked($form,
   // coordinates of the click on the button image. This means that image
   // buttons MUST have unique $form['#name'] values, but the details of
   // their $_POST data should be ignored.
-  elseif (!empty($form['#has_garbage_value']) && isset($form['#value']) && $form['#value'] !== '') {
+  elseif (!empty($element['#has_garbage_value']) && isset($element['#value']) && $element['#value'] !== '') {
     return TRUE;
   }
   return FALSE;
 }
 
 /**
- * In IE, if only one submit button is present, AND the enter key is
- * used to submit the form, no form value is sent for it and our normal
- * button detection code will never detect a match. We call this
- * function after all other button-detection is complete to check
- * for the proper conditions, and treat the single button on the form
- * as 'clicked' if they are met.
+ * In IE, if only one submit button is present, AND the enter key is used to
+ * submit the form, no form value is sent for it and our normal button detection
+ * code will never detect a match. This function is called after all other
+ * button-detection is complete to check for the proper conditions, and treat
+ * the single button on the form as 'clicked' if they are met.
  */
 function _form_builder_ie_cleanup($form, &$form_state) {
-  // Quick check to make sure we're always looking at the full form
-  // and not a sub-element.
-  if (!empty($form['#type']) && $form['#type'] == 'form') {
-    // If we haven't recognized a submission yet, and there's a single
-    // submit button, we know that we've hit the right conditions. Grab
-    // the first one and treat it as the clicked button.
-    if (empty($form_state['submitted']) && !empty($form_state['buttons']['submit']) && empty($form_state['buttons']['button'])) {
-      $button = $form_state['buttons']['submit'][0];
-
-      // Set up all the $form_state information that would have been
-      // populated had the button been recognized earlier.
-      $form_state['submitted'] = TRUE;
-      $form_state['submit_handlers'] = empty($button['#submit']) ? NULL : $button['#submit'];
-      $form_state['validate_handlers'] = empty($button['#validate']) ? NULL : $button['#validate'];
-      $form_state['values'][$button['#name']] = $button['#value'];
-      $form_state['clicked_button'] = $button;
-    }
+  if (!$form_state['programmed'] && !isset($form_state['triggering_element']) && count($form_state['buttons']) == 1) {
+    $form_state['triggering_element'] = $form_state['buttons'][0];
   }
 }
 
@@ -1526,37 +1590,35 @@ function form_state_values_clean(&$form_
   unset($form_state['values']['form_id'], $form_state['values']['form_token'], $form_state['values']['form_build_id'], $form_state['values']['op']);
 
   // Remove button values.
-  // form_builder() collects all button elements in a form, keyed by button
-  // type. We remove the button value separately for each button element.
-  foreach ($form_state['buttons'] as $button_type => $buttons) {
-    foreach ($buttons as $button) {
-      // Remove this button's value from the submitted form values by finding
-      // the value corresponding to this button.
-      // We iterate over the #parents of this button and move a reference to
-      // each parent in $form_state['values']. For example, if #parents is:
-      //   array('foo', 'bar', 'baz')
-      // then the corresponding $form_state['values'] part will look like this:
-      // array(
-      //   'foo' => array(
-      //     'bar' => array(
-      //       'baz' => 'button_value',
-      //     ),
-      //   ),
-      // )
-      // We start by (re)moving 'baz' to $last_parent, so we are able unset it
-      // at the end of the iteration. Initially, $values will contain a
-      // reference to $form_state['values'], but in the iteration we move the
-      // reference to $form_state['values']['foo'], and finally to
-      // $form_state['values']['foo']['bar'], which is the level where we can
-      // unset 'baz' (that is stored in $last_parent).
-      $parents = $button['#parents'];
-      $values = &$form_state['values'];
-      $last_parent = array_pop($parents);
-      foreach ($parents as $parent) {
-        $values = &$values[$parent];
-      }
-      unset($values[$last_parent]);
+  // form_builder() collects all button elements in a form. We remove the button
+  // value separately for each button element.
+  foreach ($form_state['buttons'] as $button) {
+    // Remove this button's value from the submitted form values by finding
+    // the value corresponding to this button.
+    // We iterate over the #parents of this button and move a reference to
+    // each parent in $form_state['values']. For example, if #parents is:
+    //   array('foo', 'bar', 'baz')
+    // then the corresponding $form_state['values'] part will look like this:
+    // array(
+    //   'foo' => array(
+    //     'bar' => array(
+    //       'baz' => 'button_value',
+    //     ),
+    //   ),
+    // )
+    // We start by (re)moving 'baz' to $last_parent, so we are able unset it
+    // at the end of the iteration. Initially, $values will contain a
+    // reference to $form_state['values'], but in the iteration we move the
+    // reference to $form_state['values']['foo'], and finally to
+    // $form_state['values']['foo']['bar'], which is the level where we can
+    // unset 'baz' (that is stored in $last_parent).
+    $parents = $button['#parents'];
+    $values = &$form_state['values'];
+    $last_parent = array_pop($parents);
+    foreach ($parents as $parent) {
+      $values = &$values[$parent];
     }
+    unset($values[$last_parent]);
   }
 }
 
Index: misc/ajax.js
===================================================================
RCS file: /cvs/drupal/drupal/misc/ajax.js,v
retrieving revision 1.9
diff -u -p -r1.9 ajax.js
--- misc/ajax.js	12 Jan 2010 06:31:22 -0000	1.9
+++ misc/ajax.js	30 Jan 2010 18:58:56 -0000
@@ -98,7 +98,7 @@ Drupal.ajax = function (base, element, e
       type: 'bar',
       message: 'Please wait...'
     },
-    button: {}
+    submit: {}
   };
 
   $.extend(this, defaults, element_settings);
@@ -121,7 +121,7 @@ Drupal.ajax = function (base, element, e
   var ajax = this;
   var options = {
     url: ajax.url,
-    data: ajax.button,
+    data: ajax.submit,
     beforeSerialize: function (element_settings, options) {
       return ajax.beforeSerialize(element_settings, options);
     },
@@ -200,10 +200,6 @@ Drupal.ajax.prototype.beforeSubmit = fun
   // Disable the element that received the change.
   $(this.element).addClass('progress-disabled').attr('disabled', true);
 
-  // Server-side code needs to know what element triggered the call, so it can
-  // find the #ajax binding.
-  form_values.push({ name: 'ajax_triggering_element', value: this.formPath });
-
   // Insert progressbar or throbber.
   if (this.progress.type == 'bar') {
     var progressBar = new Drupal.progressBar('ajax-progress-' + this.element.id, eval(this.progress.update_callback), this.progress.method, eval(this.progress.error_callback));
Index: modules/file/file.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/file/file.module,v
retrieving revision 1.18
diff -u -p -r1.18 file.module
--- modules/file/file.module	28 Jan 2010 13:56:25 -0000	1.18
+++ modules/file/file.module	30 Jan 2010 18:58:57 -0000
@@ -385,12 +385,12 @@ function file_managed_file_process($elem
     '#weight' => -5,
   );
 
-  // Because the output of this field changes depending on the button clicked,
-  // we need to ask FAPI immediately if the remove button was clicked.
-  // It's not good that we call this private function, but
-  // $form_state['clicked_button'] is only available after this #process
-  // callback is finished.
-  if (_form_button_was_clicked($element['remove_button'], $form_state)) {
+  // @todo It is not good to call these private functions. This should be
+  //   refactored so that the file deletion happens during a submit handler,
+  //   and form changes affected by that (such as toggling the upload and remove
+  //   buttons) happens during the 2nd run of this function that is triggered by
+  //   a form rebuild.
+  if (_form_button_was_clicked($element['remove_button'], $form_state) || _form_element_triggered_scripted_submission($element['remove_button'], $form_state)) {
     // If it's a temporary file we can safely remove it immediately, otherwise
     // it's up to the implementing module to clean up files that are in use.
     if ($element['#file'] && $element['#file']->status == 0) {
Index: modules/poll/poll.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/poll/poll.test,v
retrieving revision 1.28
diff -u -p -r1.28 poll.test
--- modules/poll/poll.test	9 Jan 2010 21:54:01 -0000	1.28
+++ modules/poll/poll.test	30 Jan 2010 18:58:57 -0000
@@ -341,7 +341,7 @@ class PollJSAddChoice extends DrupalWebT
 
     // Press 'add choice' button through AJAX, and place the expected HTML result
     // as the tested content.
-    $commands = $this->drupalPostAJAX(NULL, $edit, 'poll_more');
+    $commands = $this->drupalPostAJAX(NULL, $edit, array('op' => t('More choices')));
     $this->content = $commands[1]['data'];
 
     $this->assertFieldByName('choice[chid:0][chtext]', $edit['choice[new:0][chtext]'], t('Field !i found', array('!i' => 0)));
Index: modules/simpletest/drupal_web_test_case.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/simpletest/drupal_web_test_case.php,v
retrieving revision 1.193
diff -u -p -r1.193 drupal_web_test_case.php
--- modules/simpletest/drupal_web_test_case.php	15 Jan 2010 03:07:34 -0000	1.193
+++ modules/simpletest/drupal_web_test_case.php	30 Jan 2010 18:58:57 -0000
@@ -1519,11 +1519,13 @@ class DrupalWebTestCase extends DrupalTe
    *     which is likely different than the $path parameter used for retrieving
    *     the initial form. Defaults to 'system/ajax'.
    *   - triggering_element: If the value for the 'path' key is 'system/ajax' or
-   *     another generic AJAX processing path, this needs to be set to the '/'
-   *     separated path to the element within the server's cached $form array.
-   *     The callback for the generic AJAX processing path uses this to find
-   *     the #ajax information for the element, including which specific
-   *     callback to use for processing the request.
+   *     another generic AJAX processing path, this needs to be set to the name
+   *     of the element. If the name doesn't identify the element uniquely, then
+   *     this should instead be an array with a single key/value pair,
+   *     corresponding to the element name and value. The callback for the
+   *     generic AJAX processing path uses this to find the #ajax information
+   *     for the element, including which specific callback to use for
+   *     processing the request.
    * @param $options
    *   Options to be forwarded to url().
    * @param $headers
@@ -1578,7 +1580,14 @@ class DrupalWebTestCase extends DrupalTe
               $post[$key] = urlencode($key) . '=' . urlencode($value);
             }
             if ($ajax && isset($submit['triggering_element'])) {
-              $post['ajax_triggering_element'] = 'ajax_triggering_element=' . urlencode($submit['triggering_element']);
+              if (is_array($submit['triggering_element'])) {
+                // Get the first key/value pair in the array.
+                $post['_triggering_element_value'] = '_triggering_element_value=' . urlencode(reset($submit['triggering_element']));
+                $post['_triggering_element_name'] = '_triggering_element_name=' . urlencode(key($submit['triggering_element']));
+              }
+              else {
+                $post['_triggering_element_name'] = '_triggering_element_name=' . urlencode($submit['triggering_element']);
+              }
             }
             $post = implode('&', $post);
           }
Index: modules/simpletest/tests/ajax.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/simpletest/tests/ajax.test,v
retrieving revision 1.5
diff -u -p -r1.5 ajax.test
--- modules/simpletest/tests/ajax.test	12 Dec 2009 23:36:28 -0000	1.5
+++ modules/simpletest/tests/ajax.test	30 Jan 2010 18:58:57 -0000
@@ -83,63 +83,63 @@ class AJAXCommandsTestCase extends AJAXT
     $edit = array();
 
     // Tests the 'after' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'after_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'After': Click to put something after the div")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'insert' && $command['method'] == 'after' && $command['data'] == 'This will be placed after', "'after' AJAX command issued with correct data");
 
     // Tests the 'alert' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'alert_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'Alert': Click to alert")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'alert' && $command['text'] == 'Alert', "'alert' AJAX Command issued with correct text");
 
     // Tests the 'append' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'append_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'Append': Click to append something")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'insert' && $command['method'] == 'append' && $command['data'] == 'Appended text', "'append' AJAX command issued with correct data");
 
     // Tests the 'before' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'before_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'before': Click to put something before the div")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'insert' && $command['method'] == 'before' && $command['data'] == 'Before text', "'before' AJAX command issued with correct data");
 
     // Tests the 'changed' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'changed_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX changed: Click to mark div changed.")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'changed' && $command['selector'] == '#changed_div', "'changed' AJAX command issued with correct selector");
 
     // Tests the 'changed' command using the second argument.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'changed_command_asterisk_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX changed: Click to mark div changed with asterisk.")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'changed' && $command['selector'] == '#changed_div' && $command['asterisk'] == '#changed_div_mark_this', "'changed' AJAX command (with asterisk) issued with correct selector");
 
     // Tests the 'css' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'css_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("Set the the '#box' div to be blue.")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'css' && $command['selector'] == '#css_div' && $command['argument']['background-color'] == 'blue', "'css' AJAX command issued with correct selector");
 
     // Tests the 'data' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'data_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX data command: Issue command.")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'data' && $command['name'] == 'testkey' && $command['value'] == 'testvalue', "'data' AJAX command issued with correct key and value");
 
     // Tests the 'html' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'html_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX html: Replace the HTML in a selector.")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'insert' && $command['method'] == 'html' && $command['data'] == 'replacement text', "'html' AJAX command issued with correct data");
 
     // Tests the 'prepend' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'prepend_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'prepend': Click to prepend something")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'insert' && $command['method'] == 'prepend' && $command['data'] == 'prepended text', "'prepend' AJAX command issued with correct data");
 
     // Tests the 'remove' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'remove_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'remove': Click to remove text")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'remove' && $command['selector'] == '#remove_text', "'remove' AJAX command issued with correct command and selector");
 
 
     // Tests the 'restripe' command.
-    $commands = $this->drupalPostAJAX($form_path, $edit, 'restripe_command_example');
+    $commands = $this->drupalPostAJAX($form_path, $edit, array('op' => t("AJAX 'restripe' command")));
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'restripe' && $command['selector'] == '#restripe_table', "'restripe' AJAX command issued with correct selector");
   }
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.881
diff -u -p -r1.881 system.module
--- modules/system/system.module	30 Jan 2010 07:54:01 -0000	1.881
+++ modules/system/system.module	30 Jan 2010 18:58:58 -0000
@@ -327,6 +327,7 @@ function system_element_info() {
     '#name' => 'op',
     '#button_type' => 'submit',
     '#executes_submit_callback' => TRUE,
+    '#limit_validation_errors' => FALSE,
     '#process' => array('ajax_process_form'),
     '#theme_wrappers' => array('button'),
   );
@@ -335,6 +336,7 @@ function system_element_info() {
     '#name' => 'op',
     '#button_type' => 'submit',
     '#executes_submit_callback' => FALSE,
+    '#limit_validation_errors' => FALSE,
     '#process' => array('ajax_process_form'),
     '#theme_wrappers' => array('button'),
   );
@@ -342,6 +344,7 @@ function system_element_info() {
     '#input' => TRUE,
     '#button_type' => 'submit',
     '#executes_submit_callback' => TRUE,
+    '#limit_validation_errors' => FALSE,
     '#process' => array('ajax_process_form'),
     '#return_value' => TRUE,
     '#has_garbage_value' => TRUE,