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

[Abalieno]

Drupal offers two options, both not really useful. The first is to let you 
always specify the subject of the comment, the second is to lock it to the 
first words in the comment.

What I'd like is to auto fill the subject field with "Re:" followed by the 
subject of the *node*. And then leave the user the possibility to type a new 
title entirely or leave it as it is.

For example, at line 1462 of the comment module:
$form .= form_textfield(t('Subject'), 'subject', $edit['subject'] ? 
$edit['subject'] : variable_get('anonymous', 'Anonymous') , 60, 64);

This defaults the subject field to the anonymous name. I just need to know 
the exact code to replace that with the node title and add a "Re:" before 
it.

Can someone help me?

-HRose / Abalieno