This is the respective issue as https://www.drupal.org/node/1391196
The hooks for instance and widget settings, hook_field_widget_settings_form() and hook_field_instance_settings_form() both return form arrays, but receive no information at all about the larger form they're inserting into.
This means that they can't add more complex behaviours such as dependencies and ajax -- hook_form_alter has to be used instead.
That ticket was switched from D8 to D7 which back in 2013, with this comment:
Field types are no plugins, so this doesn't apply anymore to D8. I'm not even sure whether we can change those function signatures in D7 though ... feels like a won't fix to me.
Well, thankfully we have no problem with API additions in Backdrop (so long as we are not breaking backwards compatibility)...
PR by @klonos: https://github.com/backdrop/backdrop/pull/2533
Recent comments
Oh thanx ! I had an "old" text format that I had disabled. I re-enabled this format in the field body with the permissions and the field comes back for editing.
Problem of access to the body field with a simple post
See https://github.com/backdrop/backdrop-issues/issues/7148
Problem of access to the body field with a simple post
I used the theme gin for admin. Perhaps, it's the problem ? I have a color border when i selected the images and of course i used the "ctrl" key.
Small problem with multi import files images.