I am afraid that the desired functionality in currently not available in the diagram widget. Optionally, you can handle the Diagram's itemBoundsChange
event and implement youр own logic for shape size recalculation, redrawing the Visual template of a shape depending on the changed size. This approach will need a good amount of custom logic, though, as you will need to consider different scenarios in which the size of the shape is actually changed (but not only dragged to a different position).
In addition, you can also submit a feature request for such feature in our User Voice
portal if you have some time, and our developers will consider its implementation depending on the items popularity.
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