I KNOW!
You CAN'T TELL if a UI element is a clickable element element if #1, it looks just the same as everything else, #2, isn't displayed on the screen until you mouseover it!
Xcode actually REMOVED the damn disclosure arrows from hierarchical controls so that you had NO IDEA that you could click on them until you tried it.
OMF! Infuriating. Someone thought that was a good idea? Why do they still have jobs?!
What's even worse is that in some areas, the clickable items are INVISIBLE until you mouse over them. Holy crap!!
Buttons need to look like fucking BUTTONS so you can eyeball the screen and know what everything on the screen does without needing to interact with each element!
How does the "professional" design team at Apple not know this???
Flat UI design REMOVES valuable context from the user that HELPS the user figure out how the interface behaves without having to manually hunt and peck through the interface!
Ive needs to never touch a human user interface EVER.
The iOS and Mac interfaces have only gotten worse since Ive's started touching them. It's seriously tragic.