Re: [drupal-support] Locking comment subject to the node title

I made a little step forward on my own: $form .= form_textfield(t('Subject'), 'subject', $edit['subject'] ? $edit['subject'] : 'Re: '. $node->title, 60, 64); This correctly displays "Re:" But it seems that the function isn't aware of the node array. Can someone help how to import it so I can input the title on that line? The syntax seems correct but the form shows nothing because I believe the definition of the node is external.