
This code sample is not well tested.

The function itself is not fully supported by all platforms
that support FLTK, and is dependant on the user's environment.
It seems to work without any issues on Windows. I've heard it
works as well on OS X.

Linux, being a much more varied system from user to user,
is less dependable when using such environment-specific tools.
If the user runs KDE, Gnome, or a similar desktop environment,
the function will probably work without trouble. If the user
doesn't have a system-default file manager, mail client, and
web browser configured, it will likely fail in most cases.
An example is my own system, which runs a very minimal desktop
with no systemwide default programs specified. The file and mail
protocols do not work at all, and the browser protocols work only
when Firefox is already open.

