Diff view of a stashed file can be misleading

Problem

The diff you see after double-clicking a Stash can be confusing and misleading. The diff shows the difference between the file as it was stashed, and the current state of the file in the local working copy. While this might seem reasonable at the first glance, this behavior is not only inconsistent with Git, but also has various confusing effects.

Resolution

It is possible to change the git stash diff behavior with the following option: Settings (⌘ + , or Ctrl + Alt + S) > Version Control > Git > Stash | When show diff is called, compare stashed changes.