Each node has a "Flow" PanelLayout below the shape listing a bunch of text values in rows.
The context menu shown for each node has three "tabs", each showing some number of shape figures, one of which the user can click to replace the node's shape's figure. These tab panels use a "Flow" PanelLayout to arrange the shapes in rows, by setting PanelLayoutFlow.direction to 0. Note how for a custom PanelLayout one cannot use its name directly, but must construct and initialize an instance of the PanelLayout.
This extension is defined in its own file, as PanelLayoutFlow.js.
GoJS allows for the creation of custom layouts to meet specific needs.
There are also many layouts that are extensions -- not predefined in the go.js or go-debug.js library,
but available as source code in one of the three extension directories, with some documentation and corresponding samples.
More information can be found in the GoJS Intro.
GoJS can be extended in a variety of ways. The most common way to change the standard behavior is to set properties on the GraphObject, Diagram, CommandHandler, Tool, or Layout. But when the desired property does not exist, you might need to override methods of CommandHandler, Tool, Layout, Link, or Node. Methods that you can override are documented in the API reference. Various features of GoJS can be overriden, either by replacing a method on an instance (a feature of JavaScript) or by defining a subclass. You should not modify the prototypes of any of the GoJS classes.
In addition to our samples, GoJS provides an extensions gallery,
showcasing the creation of custom tools and layouts.
Those classes and samples are written in TypeScript, available at ../extensionsJSM/,
as ECMAScript/JavaScript modules -- these use the ../release/go-module.js library.
We recommend that you copy the files that you need into your project, so that you can adjust how they refer to the GoJS library
that you choose and so that you can include them into your own building and packaging procedures.
More information can be found in the GoJS Intro.