Index: misc/tabledrag.js
===================================================================
RCS file: /cvs/drupal/drupal/misc/tabledrag.js,v
retrieving revision 1.32
diff -u -p -r1.32 tabledrag.js
--- misc/tabledrag.js	3 Nov 2009 05:34:37 -0000	1.32
+++ misc/tabledrag.js	2 Dec 2009 03:24:26 -0000
@@ -83,8 +83,15 @@ Drupal.tableDrag = function (table, tabl
   // Match immediate children of the parent element to allow nesting.
   $('> tr.draggable, > tbody > tr.draggable', table).each(function() { self.makeDraggable(this); });
 
-  // Hide columns containing affected form elements.
-  this.hideColumns();
+  // Hide or show weight and parent columns according to user preference.
+  // This aids screenreader accessibility so users can enter weight values.
+  // Initialize the weight columns for the show/hide toggle.
+  self.initColumns();
+  // Add a link before the table for users to show or hide weight columns.
+  $(table).before($('<a href="#" class="tabledrag-show-weight"></a>')
+    .append(Drupal.t('Show/hide weight fields'))
+    .click(function () { self.toggleShowWeight(self); return false; })
+  );
 
   // Add mouse bindings to the document. The self variable is passed along
   // as event handlers do not have direct access to the tableDrag object.
@@ -93,10 +100,11 @@ Drupal.tableDrag = function (table, tabl
 };
 
 /**
- * Hide the columns containing form elements according to the settings for
- * this tableDrag instance.
+ * Initialize weight/parent columns to be hidden. Identify and mark each cell
+ * with a CSS class so we can easily toggle show/hide it. Finally, hide
+ * columns if user does not have a 'showWeight' cookie.
  */
-Drupal.tableDrag.prototype.hideColumns = function () {
+Drupal.tableDrag.prototype.initColumns = function () {
   for (var group in this.tableSettings) {
     // Find the first field in this group.
     for (var d in this.tableSettings[group]) {
@@ -108,7 +116,7 @@ Drupal.tableDrag.prototype.hideColumns =
       }
     }
 
-    // Hide the column containing this field.
+    // Mark the column containing this field so it can be hidden.
     if (hidden && cell[0] && cell.css('display') != 'none') {
       // Add 1 to our indexes. The nth-child selector is 1 based, not 0 based.
       // Match immediate children of the parent element to allow nesting.
@@ -128,21 +136,82 @@ Drupal.tableDrag.prototype.hideColumns =
         if (index > 0) {
           cell = row.children(':nth-child(' + index + ')');
           if (cell[0].colSpan > 1) {
-            // If this cell has a colspan, simply reduce it.
-            cell[0].colSpan = cell[0].colSpan - 1;
+            // If this cell has a colspan, mark it so we can reduce the colspan.
+            $(cell[0]).addClass('tabledrag-reduce-colspan');
           }
           else {
-            // Hide table body cells, but remove table header cells entirely
-            // (Safari doesn't hide properly).
-            parentTag == 'thead' ? cell.remove() : cell.css('display', 'none');
+            // Mark this cell so we can hide it.
+            $(cell[0]).addClass('tabledrag-display-none');
           }
         }
       });
     }
   }
+  // Now hide cells and reduce colspans unless user cookie is set.
+  var show = $.cookie('Drupal.tableDrag.showWeight');
+  if (show != 1) {
+    Drupal.tableDrag.prototype.hideColumns();
+  }
 };
 
 /**
+ * Hide the columns containing weight/parent form elements.
+ * Undo showColumns().
+ */
+Drupal.tableDrag.prototype.hideColumns = function () {
+  // Turn off display of weight/parent cells and headers.
+  $('.tabledrag-display-none').css('display', 'none');
+  // Reduce colspan of any effected multi-span columns.
+  $('.tabledrag-reduce-colspan').each(function() { this.colSpan = this.colSpan - 1; });
+}
+
+/**
+ * Show the columns containing weight/parent form elements
+ * Undo hideColumns().
+ */
+Drupal.tableDrag.prototype.showColumns = function () {
+  // Increase colspan back to columns it was reduced.
+  $('.tabledrag-reduce-colspan').each(function() { this.colSpan = this.colSpan + 1; });
+  // Turn on display of weight/parent cells and headers.
+  $('.tabledrag-display-none').css('display', 'table-cell');
+}
+
+/**
+ * Toggle visibility of weight/parent columns. Use a saved cookie to store the
+ * user preference.
+ */
+Drupal.tableDrag.prototype.toggleShowWeight = function (self) {
+  // Retrieve the tableDrag status from a stored cookie.
+  var show = $.cookie('Drupal.tableDrag.showWeight');
+
+  // Show or hide columns with weight fields and toggle the cookie value.
+  if (show == 1) {
+    $.cookie(
+      'Drupal.tableDrag.showWeight',
+      0,
+      {
+        path: Drupal.settings.basePath,
+        // The cookie should "never" expire.
+        expires: 36500,
+      }
+    );
+    this.hideColumns();
+  }
+  else {
+    $.cookie(
+      'Drupal.tableDrag.showWeight',
+      1,
+      {
+        path: Drupal.settings.basePath,
+        // The cookie should "never" expire.
+        expires: 36500,
+      }
+    );
+    this.showColumns();
+  }
+}
+
+/**
  * Find the target used within a particular row and group.
  */
 Drupal.tableDrag.prototype.rowSettings = function (group, row) {
Index: modules/system/system.css
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.css,v
retrieving revision 1.68
diff -u -p -r1.68 system.css
--- modules/system/system.css	1 Dec 2009 00:39:34 -0000	1.68
+++ modules/system/system.css	2 Dec 2009 03:24:26 -0000
@@ -688,3 +688,21 @@ div.password-confirm {
   overflow: hidden;
   position: absolute;
 }
+
+/**
+ * Hide the tabledrag 'Show weight' link for everyone but screen readers and
+ * keyboard only users.
+ */
+a.tabledrag-show-weight {
+  height: 0;
+  overflow: hidden;
+  position: absolute;
+}
+
+a.tabledrag-show-weight:focus,
+a.tabledrag-show-weight:hover,
+a.tabledrag-show-weight:active {
+  height: auto;
+  overflow: visible;
+  top: 3em;
+}