Widget upload description (filesize, allowed extensions).

Re-roll of #30.

The last submitted patch, 39: 2852808-39.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

A little bit of a safer approach since render element is used in several places.

Looks good, but will need config schema update as this prints out an error when validating with Config Inspector.

Apologies, looks good for the schema part.

Re-roll of #42

In our eyes this is an important improvement to the module. We would love to see this committed. What can be done to get this committed?