Can I add, reply and delete inline comments in the editor?

Not at this time, but we are users of our own apps, and also feel the need for this functionality.

So, we'll get to it. 

In the meantime, please comment and vote on our public Jira to indicate which part is most important to you:

• Add new inline comments:  ICE-9 - Getting issue details... STATUS
• Reply to inline comments:  ICE-8 - Getting issue details... STATUS
• Delete inline comments:  ICE-12 - Getting issue details... STATUS

By doing so, you'll then receive a notification for every status update for the particular improvement, allowing you to keep a track of its progress.