Customising apps is a joy of the past. Bundled apps can’t even have custom icons. Third-party apps can have custom icons, but anything further will break their signature.
customisation
In Mojave and Catalina, tampering with the contents of an app bundle risks breaking signature checks. Here’s how to work around that.
El Capitan’s no-go areas make many important extensions unusable now. Apple must step in and enhance OS X to compensate.
The Google Earth icon has appeared in the toolbar of every Finder window. How did that happen?
How to make your Dock transparent, or otherwise customise it.
The Eclectic Light Company 