A conversation with Zengobi Curio’s maker @georgeZengobi on the Curio forum (*tldr: found hidden settings to change zoom behaviour *) gave me the idea for this thread.
For any of the apps we all use here (Devonthink, Omnifocus, Cleanshot, etc, etc…), did you uncover some hidden settings such as the one advised by George (the kind you set in a PLIST file or equivalent) that vastly improved your experience with an app? If so, do tell! 
FWIW, the complete list of Curio’s “Advanced Power-User” (i.e., “hidden”) settings is here
https://www.zengobi.com/support/articles/Curio14AdvancedSettings.html
DEVONthink has a similar – though much shorter – list available from the Appendix of its Help pages.
The all-round champion of tweaky settings, IMO, is MacJournal, which provides the ability to add or remove from the menus almost every of the app’s commands.
I cannot say any of the “hidden” or “advanced” settings in the apps mentioned in the OP (the ones I use I listed above) have “vastly improved” anything about the app. The point of hidden or advanced settings is to provide an optional feature that the developer does not believe would appeal to all users. The problem with Curio’s and DEVONthink’s hidden settings, in particular, is that discovering which ones are turned on takes a bit of time with the Terminal and examining the configuration plist for that app. That’s why I prefer MacJournal’s approach: all the vast number of settings are all there, in a menu.
Here are similar lists of “hidden” preferences for EagleFiler and BBEdit. EagleFiler even offers these prefs as clickable links.
These kind of “hidden” user defaults are a really great way to offer custom options for rather special user requests w/o cluttering the UI for everyone.
Some back story related to this:
Along time ago, when BBEdit changed its window stacking logic to be more in line with the standard Mac behavior, I had a very hard time adopting to this change. The fine folks at Bare Bones Software couldn’t keep an old stacking option in the app’s main prefs just for a single user. But they offered to keep honoring the old user defaults option as long as it is set in the plist file. From the 9.0 (1295) release notes (in 2008):
- [NFR] Restored Matthias-mode window stacking: If you have the
old preference set, we’ll honor it. Otherwise, windows just
stack the right way, like Safari, Finder, Mail, etc.
What a great support! I was so happy about this, and I still use that option today (copying my old plist file to every new machine).
My favorite is NetNewsWire’s hidden preferences. It’s only 3 now, but the interesting part is the naming.
The first word of the PascalCaseNaming is the name of person that requested that feature! I’m sure that you will notice at least one person’s name
Interesting, all familiar names…
For a long time, BBEdit had a “Show Philip Bar” option (which displayed the window’s page guide). Guess who requested the feature.
