[development] Advanced forms api question (#submit and #programmed)

[Dave Cohen]

I'm trying to provide a patch for an issue I recently submitted 
<http://drupal.org/node/123702>.  I'm having trouble grokking some forms API 
intricacies and I'm sure someone on this list can help.

Briefly, I'm trying to customize the update.php form using hook_form_alter().  
Unfortunately update.php does not handle its form the normal way.  Normally, 
a form is created by calling drupal_get_form() and also processed by calling 
drupal_get_form().  Update.php does not do this.  My first question is why 
not?  But that is a bit off topic.

Because update.php calls drupal_get_form() only when displaying the form and 
not when processing it, changes made (in my hook_form_alter) to 
$form['#submit'] have no effect.  That is, there is no way to have my custom 
submit handler called when the form is submitted.

So, I've added a call to drupal_get_form in my copy of update.php, in the 
update_update_page method.  This does what I want, in that my #submit handler 
is called.  But there is an unwanted side-effect, which is the forms code 
then redirects the browser.  So I never get to the update.php progress page.  
So it seems I cannot add my own handler and also have update.php do its 
handling.

I poured through the forms code looking for where (and why) it does the 
redirecting.  There is a mysterious $form['#programmed'] variable which seems 
to control this, but I can't figure out what that variable is really supposed 
to be about, or where it's supposed to be set.

I feel like I'm close to solving my problem.  But I could be going down the 
wrong road.  Or perhaps there is a much simpler solution.  So I come here for 
advice.  Any help is really appreciated.  Thanks,

-Dave