ROAR should not offer 'system notification' if unsupported by OS

Description

The System Notification type that can be configured for ROAR is not supported by all operating systems.

This, for example, happens on my Ubuntu 18.04 laptop:

The option to use System Notification should only be offered when the platform can support it.

Environment

None
Fixed

Priority

Minor

Assignee

Guus der Kinderen

Reporter

Guus der Kinderen