How to get the managed_file progress bar working in a custom theme?

Question

I'm trying to get the managed_file progress bar working in a custom theme. Right now, when I start an upload, the empty progress bar widget appears in the form, but it doesn't visually update while the file is being uploaded. If I switch my site from my own theme to Bartik, the bar works properly, so it's evidently a theming problem. (This also confirms that I've got all the uploadprogress stuff properly installed.)

I've found theme_progress_bar, and tried adding it to my theme's template.php file, renaming it to MYTHEME_progress_bar, but it didn't work. Any advice on how to get it to work? Thanks!

Answer 1

Found, I think: My theme was based on Bootstrap 2, and I was getting bit by a problem of Drupal and Bootstrap disagreeing on what sort of thing the "Upload" button should be:

https://drupal.org/node/2155419

Since I'm still on Bootstrap 2 (I think) I wasn't having the problem with the input fields being out of order, but I did need to deal with the behavior assignments. In addition to the fix outlined in the cited page, I also needed to run the assignments on page load / document ready to get things properly assigned.