- Start typing a PM to somebody, but don’t send it.
- In a different tab (or window) navigate to a group you can message and click “Message”
- A dialog asks, “You already opened another draft in this topic. Are you sure you want to abandon it?” click “No, keep.”
- Note that the recipient has now changed to the group, instead of the original intended recipient of the PM.
- (Optional) skip step 4 and send the message, thereby embarrassing yourself in front of the whole group (in my case about 80 people), with several messages going back and forth before you figure out what is going on.