This strikes me as a massive UI fail on Apple's part (if *anyone* should be getting this right, it's them...).

I'm teaching myself how to use Motion. Lots of little windows and tabs. For some reason, Apple colours the tab(s) NOT in use the same colour as the pane below. How does this make sense???

Affinity Designer, the program I added the annotation in, gets it right. The active tab is the same colour as the pane below.

@MichaelPorter This seems completely broken, and reminds me of the strange behavior I started to see around iOS 7. That was rumored to be when Jony Ive took over. Before that point, every element on iOS had a Z-position, and things that were pulled up or down or over all layered in a predictable order, with UI affordances that made the order clear. That was deemed (apparently by Mr. Ive) to be too skeuomorphic and unwelcome in an all-digital world, and so the layering disappeared, and the coloring the indicating depth disappeared, and it stopped being possible to figure out what was tappable, and... whew! Bad memories.

This feels like more of that. Coloring the tabs correctly would be suggestive of the real world, and skeuomorphism is out, so instead you just have to guess that in this app, and maybe only this app, the blue text indicates the active tab. Are there only two tabs? You have a 50% chance of guessing correctly, then!