Dynamically created UI Elements are not bound by .bindInputEvents()

[rpc5102]

The internal startup function .bindInputEvents only captures session$input data that is available on init. Elements added to the UI afterwards will not have event observers attached to them for the collection of xAPI interaction statements.

This binding should only happen to each element once to prevent duplicate statement creation.

See: https://github.com/EducationShinyAppTeam/boastUtils/blob/master/R/lockerUtils.R#L38.

[rpc5102]

Needs testing 2ee8197.