Fix Incorrect Mac Dock Icon Badge Count

Fairly often, my Mac OS X 10.8 Mountain Lion “Messages” app shows the wrong number of unread messages.

Sometimes I can make the badge update after double-clicking every contact in my buddy list. With a big list, that is not a practical solution.

Instead, I’ve found that these steps seem to work:

1. Quit the problem app
2. Open Applications/Utilities/Terminal and run the following command:
   killall Dock
3. Launch the problem app