An Overview is a Diagram that displays all of a different diagram, with a rectangular box showing the viewport displayed by that other diagram.
All you need to do is set Overview.observed. For example:
var myDiagram = new go.Diagram("myDiagramDIV"); . . . other initialization . . . // create and initialize the Overview: new go.Overview("myOverviewDIV").observed = myDiagram;
The Overview draws what the observed Diagram is displaying, so setting or modifying any diagram templates or template Maps has no effect.
Animations are not shown in an Overview.
A reference to a div or its ID as a string.
Gets or sets whether this overview draws the temporary layers of the observed Diagram. The default value is true.
Gets or sets the Diagram for which this Overview is displaying a model and showing its viewport into that model.
The value must be null or another Diagram, but may not be an Overview.