Steps to reproduce:
# open a commit (differential revision) you've made, where somebody else have added an inline comment
# check "Done" checkbox on that inline comment
# press "Submit" button with "Add Comment" action selection without entering any comment text
Right now nothing happens because comment text is empty. Instead the transaction for marking inline comments Done/Undone should be created regardless of:
* selected action (Add Comment, Concern Raised, etc.)
* presence/absence of comment text.