This hook can be used for changing message data, just before the editor is displayed. This is done after escaping message data for XSS prevention is done. So in the hook, the module writer will have to be aware that data is escaped and that he has to escape data himself if needed.

This hook is called every time the editor is displayed. If modifying the message data does not have to be done on every request (for example only on the first request when replying to a message), the module will have to check the state the editor is in. Here's some hints on what you could do to accomplish this:

Beware: this hook function only changes message data before it is displayed in the editor. From the editor, the user can still change the data. Therefore, this hook cannot be used to control the data which will be stored in the database. If you need that functionality, then use the hooks ??? and/or ??? instead.

Call time:

In posting.php just before the message editor is displayed.

Hook input:

Array containing data for the message that will be shown in the editor screen.

Hook output:

Same as input.

Example code:

// Using this, an example hook function that appends the string 
// "FOO!" to the subject when replying to a message (how useful ;-) 
// could look like this:
function phorum_mod_foo_before_editor ($data)
{
    if ($data["mode"] == "reply" && ! isset($_POST["message_id])) {
        $data["reply"] = $data["reply"] . " FOO!";
    }

    return $data;
}