It is possible to use the controller when no multimedia is available

When the system has no media source and user opens the application the control buttons are not disabled and can be clicked. The same behavior is when the last media source application is closed.

Start by running the application with no media source, then close the last media-source application and observe the controller buttons in both cases. Trace the controller UI state handling from those entry points; done means the control buttons are disabled when no multimedia source is available at startup and after the last source closes.

Written by the indexing model from the issue text.