Edit: Feature-request: Add a "stack count" before stacked messages to reduce possible confusion. Like
 comment on QUESTION
Whenever someone posts an answer to your question, or a comment under your post, or a comment that mentions you, you get a inbox message, represented on top right with a number on red background. The number is right how many message you've got and unread.
However I often see the number displayed is wrong, mostly shifted up by 1. That is, for example, I have 2 new items, but the number shows 3 (as shown below, I definitely have read those 9 hr ago items).
I'm not quite clear how to reproduce this issue, but it seems like this issue occurs more frequently in this way:
1. Get 2 or more inbox items
2. Read some of them, but not all, then quit
3. Get some more inbox items
Now the number is possibly wrong.