Is Fizzygum really an Operating System?

Fizzygum does not sit directly on the hardware layer managing hardware resources.
So, according to the standard definition, Fizzygum is not an Operating System.

However, Fizzygum provides many abstractions that are commonly provided by OSs:

  • processes and process management (widgets are also processes)
  • scheduling ( ↔ stepping)
  • forking ( ↔ duplication of widgets)
  • inter-process communication ( ↔ connections)
  • files/folders ( ↔ shortcuts to objects / folders)
  • rich and cohesive graphical user interface¹

For related discussions regarding how languages/environments do/could (/should?) completely wrap the OS layer (so that the OS layer is never exposed directly to users), see:

¹graphical user interfaces are not strictly part of an OS. However the two mainstream desktop/mobile OSs ship with a deeply-integrated non-swappable graphical user interface software layer.