theme_progress_bar should have more information about when to use function

 /**
  * Returns HTML for an indentation div; used for drag and drop tables.
+ * Note that this is only used for non-javascript batch jobs.
  *
  * @param $variables
  *   An associative array containing:

Sorry you posted, while I did^^

aww...

OMG, commented the wrong function... -.- clearly too late!

This is the right one:

 /**
  * Returns HTML for a progress bar.
+ * Note that this is only used for non-javascript batch jobs.
  *
  * @param $variables
  *   An associative array containing:

you mean

 /**
  * Returns HTML for a progress bar.
  *
+ * Note that this is only used for non-javascript batch jobs.
  *
  * @param $variables
  *   An associative array containing:

?

Sorry! This one hopefully..

For shure, anyone can use this function to make his own progress bars.

Note that this is only used for non-javascript batch jobs.

batch.inc:
in function _batch_progress_page_js()
returned markup is hardcoded and simply <div id="progress"></div>
the progressbar markup will later by added by javascript without using theme_progress_bar

in function _batch_progress_page_nojs()
it uses return theme('progress_bar', array('percent' => $percentage, 'message' => $message));

Is there something you would change on the sentence?

Hmm lets say somone uses this theme function, I think he won't implement a new batch system..

The thing I really want to point out is that..

Drupal's core Batch API uses this only for non-JavaScript batch jobs.

That anyone can use this for his own stuff like a in-page progress bar (without using the batch API) should be clear anyway

you understand what I mean?^^

Okay, I hope this one is clear:

/**
 * Returns HTML for a progress bar.
 *
 * Note that the core Batch API uses this only for non-JavaScript batch jobs.
 *
 * @param $variables
 *   An associative array containing:
 *   - percent: The percentage of the progress.
 *   - message: A string containing information to be displayed.
 */

Yep, is there already a new implementation of the Batch API planned yet?

attached rerolled patch against d7