How modular and flexible is the Toga for adding other backends (GUI)?

[Heus-Sueh]

Would it be too difficult to add other backends or is the problem the time it would take to accomplish this task?

[freakboy3742]

Toga has been specifically built so that backends are completely pluggable, and can be contributed or maintained by a third party.

To define a new backend, create a normal Python package; in that package's metadata, declare a dependency on toga-core, and register a toga.backend entry point. Using PEP621 metadata, you could expose a custom backend for Windows users with:

[project.entry-points."toga.backends"]
windows = "togax_custom_backend"

togax_custom_backend is the name of the python module that is provided by your Python package. You should not use the toga prefix in your package name - we're reserving that for official packages. User contribute packages should use the togax prefix.

This package should have a togax_custom_backend.factory module; that provides the namespace that Toga will use to construct platform-specific objects like App, Window and Button.

As long as toga-core and togax_custom_backend are both installed on Windows, your custom backend will be used. If there is more than one valid backend for the current platform (e.g., if you had your custom backend and toga-winforms installed), you will need to specify which one to use, by setting TOGA_BACKEND=togax_custom_backend in your environment.