Correct, the grid gives this as an example for between two grids.
With this explanation:
On initial analysis, consideration was given to exposing callbacks or firing events in the grid for the drop zone relevant events e.g.
onDragEnter,onDragExitetc. However this did not add any additional value given that the developer can easily add such event listeners to the grid div directly.
Now, since it is not as easily done in Dash, for obvious reasons. We have to design our own way.
Technically, this isn’t directly supported but just an example of how to utilize the tools provided by the grid to be able to do such things.
You can personally add event listeners directly to the outside div, by using a clientside callback. The main thing is that the grid needs to get rowManagedDrag: True via the dashGridOptions.