Editing a node with CCK image_fupload widget in single upload mode produces javascript error

The image_fupload CCK widget bails in favor of the standard image upload widget when editing an existing node:

      // standard image fupload form; will be shown in the most cases (not for existing node in single mode)
      if (isset($form['#node']->nid) && $field['widget']['fupload_mode'] == "single") {
        // don't create fupload form

which makes sense. However the swfupload-settings.tpl.php gets included regardless. Since the span '#spanUploadButton' never gets added to the form, this produces a JS error:

uncaught exception: Could not find the placeholder element: spanUploadButton

The attached patch does two things:

• it uses Drupal.behaviors to initalize the swfupload object instead of window.unload, which shouldn't be used anymore, and
• It does a simple check to see if #spanUploadButton exists, and doesn't try to create the swfupload object if not