Providing a comment should not be mandatory (because one can always write a fake message) but highly encouraged when flagging an issue as "false positive" or "won't fix".
So for instance, here's what we could do:
- the user clicks on "Resolve as won't fix"
- the issue is actually set as "Won't Fix" and at the same time, a comment popup shows up with a message at the top: "Please tell why?"
- if the user presses "Esc", the popup just disappears