If I install paint.net without Microsoft store, it will ask if I want to use it as the default image editor. If I install through the Microsoft Store (because I want to support paint.net), there is no such option. I've tried changing the default image editor in the registry, but if I try to launch PaintDotNet.exe in the Microsoft Store (C:\Program Files\WindowsApps\dotPDNLLC.paint.net_4.210.7348.0_x64__h55e3w7q8jbva) installation location using Explorer, I get an error saying that SetupNgen.exe and SetupNgen.exe.config are missing. I've tried copying the files from the original install location (C:\Program Files\paint.net), but I can't get the permissions working right.
Since the Microsoft Store version costs money, I think the option to use it as the default image editor should be presented just like the regular version.