Make it possible to add sub-tabs to Sankey examples.

modules/d3_sankey_examples/d3_sankey_examples.module

@@ -26,6 +26,16 @@ function d3_sankey_examples_menu() {
     'type' => MENU_LOCAL_TASK,
   );
 
+  // We want the Sankey tab to have sub-tabs so we can add examples for
+  // preprocessed data, but the default sub-tab needs to have the same settings
+  // as the parent tab, except for the type, title, and description.
+  $items['d3/examples/sankey/default'] = array(
+    'type' => MENU_DEFAULT_LOCAL_TASK,
+    'title' => 'Raw data',
+    'description' => 'Creates a Sankey chart by specifying raw data.',
+    'weight' => -1,
+  ) + $items['d3/examples/sankey'];
+
   return $items;
 }