UI hard to work with

[Pšenda]

48 minutes ago, Old Bruce said:

Case in point, Active tab is Light, Active Preference is Dark.

Although I don't know exactly what you mean (maybe it will be clarified by the missing picture), it makes sense to me - the active tab is bright because it stands out above the others inactive, and is therefore lit against them. In contrast, the preferences button is active when pressed, making it darker than other buttons because it is in the shadows.

[R C-R]

1 hour ago, Pšenda said:

Although I don't know exactly what you mean (maybe it will be clarified by the missing picture), it makes sense to me - the active tab is bright because it stands out above the others inactive, and is therefore lit against them. In contrast, the preferences button is active when pressed, making it darker than other buttons because it is in the shadows.

But on Macs, both reverse when switching from the Dark to the Light UI.

[Old Bruce]

1 minute ago, R C-R said:

But on Macs, both reverse when switching from the Dark to the Light UI.

And the metaphor then becomes the Active button has its light turned on instead of it is depressed and therefore in shadow. 

It is just bad design. Being different for the sake of being different, instead of using a metaphor and using that metaphor consistently. Are they buttons which are depressed or buttons that light up?

[Pšenda]

1 hour ago, R C-R said:

But on Macs, both reverse when switching from the Dark to the Light UI.

I don't use Light UI - I'm not interested in its logic, nor am I trying to understand it.
I assumed it was talking about a standard graphics application interface, that is, a dark interface.

[R C-R]

2 hours ago, Pšenda said:

I don't use Light UI - I'm not interested in its logic, nor am I trying to understand it.
I assumed it was talking about a standard graphics application interface, that is, a dark interface.

For Macs running recent OS versions, both the Light & Dark UI are system level "standards." In System Preferences > General > Appearance there is a choice of Light, Dark, or Auto. I think but am not sure that Light is the default. According to the tooltip, Auto adjusts the UI "throughout the day."  

For the Affinity apps running those recent macOS versions, the choices are Dark, Light, & OS Default. For me, OS Default sets the UI to Light, not Dark, but that might change if I used the system level auto setting.

Anyway, the bottom line is for Macs there is more than one standard graphics application interface.