IMPORTANT:
If you handled the FDF POSTs via $HTTP_RAW_POST_DATA as in user contributed scripts above, it's good to know that once you decide to rebuild PHP with FDFToolkit support, $HTTP_RAW_POST_DATA will be undefined.
Good news - $HTTP_FDF_DATA _will_ be defined instead. (Look at the example above).To get the user contributed scripts working in both plain PHP and PHP+FDFToolkit use
$HTTP_RAW_POST_DATA . $HTTP_FDF_DATA
where $HTTP_RAW_POST_DATA mentioned.
Dimitri Tarassenko