Index: includes/ajax.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/ajax.inc,v
retrieving revision 1.41
diff -u -p -r1.41 ajax.inc
--- includes/ajax.inc	23 Dec 2010 04:26:31 -0000	1.41
+++ includes/ajax.inc	26 Dec 2010 00:31:23 -0000
@@ -587,13 +587,8 @@ function ajax_pre_render_element($elemen
       case 'submit':
       case 'button':
       case 'image_button':
-        // Use the mousedown instead of the click event because form
-        // submission via pressing the enter key triggers a click event on
-        // submit inputs, inappropriately triggering AJAX behaviors.
-        $element['#ajax']['event'] = 'mousedown';
-        // Attach an additional event handler so that AJAX behaviors
-        // can be triggered still via keyboard input.
-        $element['#ajax']['keypress'] = TRUE;
+      case 'link':
+        $element['#ajax']['event'] = 'click';
         break;
 
       case 'password':
@@ -608,10 +603,6 @@ function ajax_pre_render_element($elemen
         $element['#ajax']['event'] = 'change';
         break;
 
-      case 'link':
-        $element['#ajax']['event'] = 'click';
-        break;
-
       default:
         return $element;
     }
Index: misc/ajax.js
===================================================================
RCS file: /cvs/drupal/drupal/misc/ajax.js,v
retrieving revision 1.35
diff -u -p -r1.35 ajax.js
--- misc/ajax.js	23 Dec 2010 04:26:31 -0000	1.35
+++ misc/ajax.js	26 Dec 2010 00:31:24 -0000
@@ -41,7 +41,7 @@ Drupal.behaviors.AJAX = {
     $('.use-ajax:not(.ajax-processed)').addClass('ajax-processed').each(function () {
       var element_settings = {};
       // Clicked links look better with the throbber than the progress bar.
-      element_settings.progress = { 'type': 'throbber' };
+      element_settings.progress = {'type': 'throbber'};
 
       // For anchor tags, these will go to the target of the anchor rather
       // than the usual location.
@@ -55,7 +55,7 @@ Drupal.behaviors.AJAX = {
 
     // This class means to submit the form to the action using AJAX.
     $('.use-ajax-submit:not(.ajax-processed)').addClass('ajax-processed').each(function () {
-      var element_settings = {};
+      var element_settings = {event: 'click'};
 
       // AJAX submits specified in this manner automatically submit to the
       // normal form action.
@@ -63,14 +63,24 @@ Drupal.behaviors.AJAX = {
       // Form submit button clicks need to tell the form what was clicked so
       // it gets passed in the POST request.
       element_settings.setClick = true;
-      // Form buttons use the 'click' event rather than mousedown.
-      element_settings.event = 'click';
       // Clicked form buttons look better with the throbber than the progress bar.
-      element_settings.progress = { 'type': 'throbber' };
+      element_settings.progress = {'type': 'throbber'};
 
       var base = $(this).attr('id');
       Drupal.ajax[base] = new Drupal.ajax(base, this, element_settings);
     });
+
+    // Browsers trigger the click event of the first submit button when ENTER is
+    // pressed from a textfield. When there is more than one submit button, this
+    // usually leads to untuitive behavior, so disable this browser feature.
+    // @todo This probably does not belong in ajax.js.
+    $('input:text', context).once('TODO-NEED-NAME', function() {
+      $(this).keypress(function(event) {
+        if (event.which == 13 && $('input:submit, input:image', this.form).length > 1) {
+          event.preventDefault();
+        }
+      });
+    });
   }
 };
 
@@ -99,8 +109,8 @@ Drupal.behaviors.AJAX = {
 Drupal.ajax = function (base, element, element_settings) {
   var defaults = {
     url: 'system/ajax',
-    event: 'mousedown',
-    keypress: true,
+    event: 'click',
+    keypress: false,
     selector: '#' + base,
     effect: 'none',
     speed: 'none',
Index: modules/field_ui/field_ui.js
===================================================================
RCS file: /cvs/drupal/drupal/modules/field_ui/field_ui.js,v
retrieving revision 1.8
diff -u -p -r1.8 field_ui.js
--- modules/field_ui/field_ui.js	21 Nov 2010 08:50:49 -0000	1.8
+++ modules/field_ui/field_ui.js	26 Dec 2010 00:32:05 -0000
@@ -236,7 +236,7 @@ Drupal.fieldUIOverview = {
 
       // Fire the AJAX update.
       $('input[name=refresh_rows]').val(rowNames.join(' '));
-      $('input#edit-refresh').mousedown();
+      $('input#edit-refresh').click();
 
       // Disabled elements do not appear in POST ajax data, so we mark the
       // elements disabled only after firing the request.