Although the different Fyne drivers have potentially different supported platforms, the core toolkit just supports a standard set of operating systems. At the time of writing, this covered macOS, Windows, Linux, and BSD variants. Any operating system-specific code understands how applications should function on each of these target. Unlike the other toolkits in Section 3, Modern Graphical Toolkits, Fyne is designed to provide APIs for managing applications as well as their graphical interfaces. For example, app.OpenURL() allows an application to launch an external document in the default browser for each supported system.

Now that we've explored the Fyne project background, as well as its design and operating system support, let's explore the APIs it provides to application developers.