Issue with Ctools form wizard, proposed solution + patch

Ok so I am running Drupal 6.20, and need the hierarchical_select api to generate some form fields in a ctools wizard form.

Ran into major issues with server errors getting returned in the json call to 'hierarchical_select_json'. Here's what I discovered about the error:

• An "unsupported operand types" error is getting thrown from line 2946 in Drupal's /includes/common.inc (using Drupal 6.20)
• Upon further investigation, I found that this error is getting triggered by a drupal_render() call inside of the hierarchical_select_json() function.
• When I ran a dpm() call on the cached data retrieved in this function, I found that the form id and the parameters were missing from the cached array.
• The result is that empty data was being sent to drupal_render() and causing the error.

Here's how I solved it:

• I call out to a new hook inside of hierarchical_select_after_build, the function that sets the cached form info that hierarchical_select_json() expects
• This hook is called hook_hs_parameters_alter, and expects an array of parameters. It also returns an array of parameters.
• Inside my module's hook implementation, I manually set the form id and the 'form_load_files' array.

There was one slight complication relating to ctools.

The ctools form wizard step functions have a different signature than drupal's form api exects from a form builder function.
The expected FAPI signature is my_form(&$form_state, $params....)
The form wizard expects something like this: my_form(&$form, &$form_state)

So... I had to create a wrapper function and specify the wrapper function in my hook_hs_parameters_alter() implementation.

SO, tying it all together, here's what I have.

Change to hierarchical_select.module, within hierarchical_select_after_build():

    $parameters = (isset($form['#parameters'])) ? $form['#parameters'] : array();
    $menu_item = menu_get_item();

     // Here's the new code:
    foreach(module_list() as $module) {
      if (function_exists($module . "_hs_parameters_alter")) {
        $parameters = call_user_func_array($module . "_hs_parameters_alter", array($parameters));
      }
    }

    // Collect information in this array, which will be used in dynamic form
    // updates, to …
    $storage = array(

my_module/includes/wizard_step_1.inc

function wizard_step_1_form(&$form, &$form_state) {
   // Define hierarchical select element, among other things, here.
}

// Here's my wrapper that hierarchical_select_json() will invoke
function wizard_step_1_form_wrapper(&$form_state) {
   $form = array();
   wizard_step_1_form($form, $form_state);
  return $form;
}

my_module/my_module.module:

function my_module_hs_parameters_alter(&$parameters) {
  $parameters[0] = 'wizard_step_1_form_wrapper';
  $parameters[1]['form_load_files'][] = drupal_get_path('module', 'my_module') . "/includes/wizard_step_1.inc";
  return $parameters;
}