Using AHAH on custom elements is not possible

This lets us remove the #cache from the AHAH poll edit form and that gives us an excellent opportunity to test the changes. Of course, book and menu could see #cache removed but I would rather not distrurb them when the whole of parent chooser is being rehauled...

All in all, after this patch is in we can have standalone form elements that use AHAH like the drilldown in http://drupal.org/node/191360 . It's good I am doing such a complex form, all these flaws surface before release. Yay.

More comments.

Well, there is a bit more than the above that's needed. One, I factored out drupal_rebuild_form because that's needed and also I added an #array_parents to make it easier to find ourselves.

Same code just added Eaton-amount ;) comments.

Then send back a part of the returned form. $form_state['clicked_button']['#array_parents'] will help you to find which part.

So you are an element somewhere in the form tree. How will the AHAH callback find the element in the rebuilt form? Currently it has no way unless you set #tree TRUE on the form root when #parents becomes the same as the new #array_parents. With #array_parents, and a rebuilt form, you can take the $form_state['clicked_button']['#array_parents'] and do (actual code from menu_form_js):

  $form = drupal_rebuild_form($form_id, $form_state, $args, $form_build_id);
  // Pick up the parents of the pressed button.
  $array_parents = $form_state['clicked_button']['#array_parents'];
  // The last parent is the button itself, we need the wrapper instead.
  array_pop($array_parents);
  while ($array_parents) {
    $parent = array_shift($array_parents);
    $form = $form[$parent];
  }

And then you have $form ready to be sent back to the client. You just walk the form tree the same way as in the original form. #array_parents is the thread of Ariadne.

Note: The _form_builder_handle_input_element change is just a cleanup as we longer pass a variable number of arguments, we can just use $function which results in simpler code.

(this from the original post)

What's a form rebuilding? and the clears typo is fixed in the attached patch. Also in the future could you please tell me on IM too if you have problems like this -- a five minute, trivial comment change now postponed the patch for another day :(

I said "too". A simple "http://drupal.org/node/193191#comment-634164" on Skype is more than enough because then I know I need to deal with something.

Fixed the summary to be one line.