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From the online Painting brush strokes help topic in the Modifier keys section: ⌥ is the symbol Apple uses for the alt/option key.

Look carefully. Does it say MB or MP? MB means megabytes. MP means megapixels.

Finder & Quick View can do all of that.

Sure ... but graphics editors operate in the virtual digital realm where everything is not really real.

Is this because the Live Procedural Texture filter only works with RGB channels? I seem to remember that being mentioned somewhere but I can't find a reference to that limitation, either by searching the forums or in the help topics. Assuming I am remembering this correctly, is there any intention of adding support to this live filter for LAB, Greyscale, etc. channels?

It doesn't help that "color space" is often used as a sort of catch-all phrase that variously can mean a color model, any of several abstract mathematical spaces, a color format (color space + bit depth), a particular indexed or discrete color scheme, sometimes even a specific ICC profile, or almost anything else that refers to digitized color representations. It also doesn't help that even complex abstract mathematical models cannot accurately model how we perceive colors, or for that matter that human vision is a dynamic process cameras cannot duplicate.

I noticed you used an 'expand stroke' step in the video. The OP mentioned that in the screenshots the curves were stroked & their fill colors were "hidden". I'm not sure if that means the fill color(s) were temporarily set to no color or what, but if each curve was originally a simple shape with a stroke & fill, I don't think the end result would be quite what the OP wanted, assuming it was a single shape that could be filled with a color covering the inside of the overall shape.

If that is what the OP means, then while in the Develop Persona, making sure View > Studio > Details is enabled (has a checkmark) should reveal it.

@KCP, it would help if you can attach the .afdesign file with the 4 shapes in it to a post so we can see how they are constructed.

I am not sure what you mean by "details panel." If you do not know the official name of the panel, can you explain what it does or looks like? Also, which Affinity app are you using?

It sounds like you are working with an "(Image)" layer.

Nope. https://www.merriam-webster.com/dictionary/unclip. First known use of unclip was in 1874.

Maybe it doesn't make any sense but at least for the SP fonts included in some of the iOS Assets Apple's licensing restrictions are very clear -- to install those fonts from the dmg download, you have to agree to those terms to install them, just like for most of Apple's other stuff.

I have no idea why you think a majority of definitions somehow invalidates the others.

Maybe I don't understand what you want to do, but why not delete the selected background in Photo? Why invert the selection?