There is a https://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_buildForm manual page, but not sure I've got it right.
Say, there is a value in a custom function, which should be set as default in a form, built using hook_buildForm (where form itself opens in a modal frame and outside civicrm/ path).
I've a suspicions CRM_Utils_Array::value might be used to set a custom variable somewhere (anywhere) and get it later on wherever it might be needed;
Have an attempt to set value outside of hook_buildForm like this:
$myVeryOwnPid = CRM_Utils_Array::value('myveryownpid', $contact['contact_id_b'], $contact['contact_id_b']);
and get it from inside hook_buildForm:
$myVeryOwnPid = CRM_Utils_Array::value('myveryownpid', $_GET, '0');
..but, of course, nothing works, just because I clearly don't understand, how it should work. As they say, CRM_Utils_Array is the most often used feature in CiviCRM, but digging inside a source code Ive realized there is no forest for the trees (at least, for me). Any advice, please!