Prevent unauthenticated users from trying to comment on designs
Problem
When viewing a design on an issue without being logged in, the UI prompts you to either "Click the image where you'd like to start a new discussion" or respond to a discussion with a reply box like this:
It is not until after the user writes the comment and then tries to submit it that the system says they could not add a comment to the design:
It is also unclear in this case why you cannot add a comment, even though I now know it is because you need to be logged in.
Proposal
We should do something similar to what we do on issues when the user is not logged in and prompt them to sign in or register before they are allowed to comment.
Edited by Matt Nohr