The HTML5 "multiple" attribute allows multiple files to be selected and uploaded at once. In Backdrop, we should integrate this into the "managed_file" element and the File module field.
Sub-issue of https://github.com/backdrop/backdrop-issues/issues/200
This should be relatively portable from Drupal 8.
Commit: http://drupalcode.org/project/drupal.git/commit/8fd2b4779ec83c3e44a8caac... Issue: http://drupal.org/node/625958
~~PR by @docwilmot: https://github.com/backdrop/backdrop/pull/2430~~ ~~PR by @quicksketch (based on @docwilmot's): https://github.com/backdrop/backdrop/pull/3030~~ PR by @docwilmot: https://github.com/backdrop/backdrop/pull/3755
GitHub Issue #:
440
Recent comments
For such cases I like EVA https://backdropcms.org/project/eva
Display field using content of another field
If you don't want/need a View, I think Computed Field would be an excellent option for this. BTW, you can use token replacement (by using the function token_replace()) in the computation of the field...
Display field using content of another field
Views would be my first port of call, but I guess you've already thought of that. I haven't used it but you could also look at Views Field Formatter
Display field using content of another field