Earlier quoted context omitted.
There's a pretty simple settings window: https://github.com/domenic/display-blackout?tab=readme-ov-fi... Would that UI be hard to accomplish?
You mean conceptually or to match it? Native components are pretty much impossible to match without actually using the native framework which provides them, so you need WinUI/WPF. Win32 provides its own components which are basically Win95 style apps, and you can draw the components using some graphics APIs by yourself. The whole native development area is a mess exactly because making your own (decent) renderer is a…
I came from the WinForms world so don't pretend I don't understand Win32 programming. The fault lies with Microsoft for not investing in it more.