Multi-file uploads in Drupal 8?

EDIT (20.4.2013): This has been committed and is now part of D8 core.

Back at DrupalCon Munich code sprint I started to work on a core issue that is focused on implementing HTML5 multiple uploads support in Drupal. Since I've always been interested in file handling I immediatley found this very attractive. From the other hand I always strugeled when it comes to files in Drupal. There are so many solutions and none of them is really user friendly. I thought that this feature would make Drupal's UX much better. During my travel back home from Munich and the days after I spent some time working on the issue, but then it stuck somwhere in the middle due to my lack of time.

In January I started to work for where I got so-called Drupal day at the end of every sprint. That helped me to focus on this issue once again (and I am very thankful for that). During last 2 or 3 weeks I managed to finish the patch (in terms of features):

  • file and managed_file FAPI elements have been updated to accept #multiple option. Once this option is enabled element adds "multiple" argument to it's input tag, which enables multi-file uploads in recent versions of all major browsers. Old browsers should gracefully degrade to single-upload without any problems. 
  • File & Image field widgets leverage new #multiple option in it's underlaying form elements to improve experience for multi-value fields. Users will no longer upload galleries on file at a time. Everything can be now done in a single step.
  • Existing tests were corrected to pass with newly added features (FAPI element behaviour changed a bit).

I've already been testing, but patch still needs a lot of testing and reviews. More information can be found in the issue queue.