MapDockFactory

A DockFactory, implemented by a simple Map.

This only works when all Docks are created at application start-up. It cannot create docks on-demand.

Docks would be created, and stay in memory for the entire lifetime of the Harbour, even if they are never used.

On the plus side, toggling the visibility of docks (e.g. via ToggleMenuItems) is easy : Bidirectionally bind ToggleMenuItem.selectedProperty and Dock.visibleProperty.