We had not one but two regressions1An issue found in an update that was not in the prior release in Name Mangler 3.7.2, one of which broke the licenses for anyone who had upgraded to Name Mangler 3 from Name Mangler 2. As a result, these users thought this was a paid update, which it clearly was not. You can read more about this in the release notes.
The other issue was that the Clear List menu item would become disabled after a renaming operation.
The good news is that Name Mangler 3.7.3 fixes both issues, and is available now for direct users, and should be available shortly, if not already, for App Store users. (The license issue didn’t affect the App Store version, given Apple controls the licensing for apps in the store.)
Many Tricks

