I was syncing with Dropbox, and Mental Case 2.3 lost my data. How do I get it back?

Mental Case 2.3 introduced sandboxing, which is now a requirement for all apps in the Mac App Store. If you were using Dropbox syncing, with a symbolic link to the Library folder, the migration to sandboxing will not import your data properly.

Here is the fix:
1) Remove the symbolic link at /Library/Application Support/Mental Case
2) Drag that data back from Dropbox to the place where the symbolic link was
3) Go to the folder

/Library/Containers

4) Move the folder com.mentalfaculy.mentalcase.mac to your Desktop
5) Launch Mental Case 2.3. It should copy the Library folder you moved from Dropbox into the new Container, and it should work after that.

Note that to get to the /Library folder, which is hidden, you need to select your home folder in Finder, and then choose Go > Go to Folder, and enter 'Library'.