If you look into the View menu there is a "Current Position" menu entry which is deactivated by default. If you click it a new tab will appear on the left in the sidebar that displays information about the current position.

The "Current Position" tab is deactivated by default because we don't want to overwhelm non-gpx users with information.

There is another hidden tab that you can display by starting Marble with

marble --enableFileView

This task is about creating another menu entry below the "Curren Position" menu entry with the name "File View". The File View tab should be hidden by default. Toggling the "File View" menu entry will toggle the appearance of the "File View" tab.