I'm not sure if this is covered by #160 but it's not explicitely mentioned there. There are two issues with the Folding story compared to mxGraph[1]:

• There is no button to expand the vertex.
• Trying to drag one vertex into another causes an error cell is null.

Error in the console when dragging (with v0.4.0)

Uncaught TypeError: cell2 is null
    isLayer GraphDataModel.js:374
    getDropTarget SwimlaneMixin.js:280
    mouseMove SelectionHandler.js:759
    fireMouseEvent EventsMixin.js:640
    installListeners GraphView.js:1684

About the dragging error, this may relates to #357 which has been fixed in v0.9.0.

[1] https://jgraph.github.io/mxgraph/javascript/examples/folding.html