VASSAL Reference Manual
Adds a separate "Mini Map" subwindow that can be displayed over the top of the main map display.
The Overview map can be displayed by a Toolbar Button or by a Hotkey.
The subwindow will contain a view of the entire playing area at a smaller scale than displayed in the parent map window.
The area of the map currently visible in the map window is highlighted in the overview map with a colored rectangle. A player may click on the Overview window to center the Map Window at the point clicked on.
A Toolbar button to turn this subwindow on and off will be placed on the Map Window’s toolbar A hotkey or Named Key Command can also be supplied to open the mini map subwindow.