[Suggestion] Closing mentions from inbox should mark them as read

When I first saw the Inbox feature, I was glad that I could finally see all the messages that pinged me at once. Not too glad after I closed it, expecting it to get rid of the ping, but the ping stayed on the server it came from. Still had to either Mark All Messages as read or jump to the message from the inbox (which could take ages) and scroll around for a bit to mark it as read. 

Tl;dr closing mentions from the inbox should get rid of the red circle ping