If instead of insisting on custom UI styling the author just used the system UI, they could probably build a pretty straightforward Windows application. It’s the scourge of “brand identity” that has people thinking graphical applications are hard.
Same on the Mac: If you want to build a Mac application, your best bet will be AppKit or SwiftUI and using system controls. And when the OS updates your application will either update with it, or need only minor tweaks and a rebuild to look good.
This indeed. Custom UI widgets for Windows apps are really not necessary most of the time, and fitting in with the system theme is all you ought to aim for, most of the time.
There are exceptions, for very rich dense UI, for UIs that need to be cross-platform, but if you're writing a Windows app, it should look and feel like a Windows app.
My experience with SwiftUI on the Mac is that it still needs a lot of work. Documentation is poor. Performance can be bad if you do things in a straightforward way. Supporting older versions of the OS is quite painful etc.
