When the id of a post is specified in get_the_title($id), it is not always possible to get the ID of the post in the 'the_title' filter, since the post is not necessarily held in $post. For a good example of this see the' Activity Box' on the Dashboard.
One reason one would want the id is to modify the title with, e.g. values held in custom fields.
I propose that the id is passed as an argument to the 'the_title' filter as follows:
function get_the_title($id = 0) {
...
return apply_filters( 'the_title', $title, $post->ID );
}
Which would always make the (correct) id available to the filter.
Cheers,
Henrik.
