[Javascript] Help : writting to message box in iframe

[javascript@xxxxxxxxxx (Harry Love)]

<snip>
            <div id="html_viewer_message" class="html_editor" 
style="background-color:white;position:relative;top:-2px;">
                <iframe id="styled_text_message" 
name="styled_text_message" style="height:250px;font-family:Arial, 
Helvetica"></iframe>
            </div>


On  selecting an appropriate parameter, I need to append the value in 
the above form field with the 'code'  using Javascript.  However I am 
having trouble referring it. The code that I am currently looking at is

document.all.styled_text_message.value += '\n' + code + '\n';
</snip>


Are you looking for something like this?
document.getElementById("styled_text_message").value += ...

Note: the success of this solution depends on the browsers you're trying
to support.  Your original message did not indicate a preference, so I'm
using a DOM reference to the object.

HTH,
Harry