Thanks for your awesome library!
I have a suggestion. Since hotkeys for Linux work only for X11, then could you add a function that checks if the platform is supported? This can be convenient if I want to show the user in the UI that hotkeys cannot be registered.
This can be implemented by adding a function that returns true for Windows and Mac, and QX11Info::isPlatformX11() on Linux.
I can make a PR if you approve my suggestion.