textarea.js bug?

I set a custom padding on textarea (contact form):

#contact-mail-page .form-textarea {
  padding: 5px;
}

The following code in "textarea.js" don't take the padding into consideration:

  grippie
     .insertAfter(textarea)
     .css('margin-right', grippie.width() - textarea.width());

The textarea looks weird: http://img136.imageshack.us/img136/1736/textarea.jpg
This problem doesn't exist in drupal 6. I think, something is messed up in textarea.js.

You can reproduce the bug using a padding on textarea.