Since Final Cut Pro 10.0.0, there has been a secret debug menu, that's not user accessible.
You can explore the debug menu by following these steps:
Install Xcode if you don't already have it.
Install NibDecompiler using the instructions on their GitHub README.
Make a duplicate of your Final Cut Pro application for safety.
Right click on the Final Cut Pro application bundle and select "Show Package Contents".
Navigate to "Contents > Resources > en.lproj" (assuming your system is set to English).
MainMenu.nib file to your desktop.
Right click on the
MainMenu.nib file and select "Services > NibDecompiler".
Double click on
MainMenu.nib to open it in Xcode.
If presented with a "Trust opening older file format?" warning, select "Open and Upgrade".
If presented with a "The document MainMenu.nib has an internal inconsistency that was found and repaired", select "OK".
Select the "Debug" menu in the Interface Builder and press CMD+D to duplicate it.
MainMenu.nib file from your desktop back into your Final Cut Pro application, replacing the original.
Now when you open Final Cut Pro, you'll have access to the Debug Menu.