@Yohdu said:
My second and main question is then : how to implement correct drag and drop operations with custom QStandardItem which needs to own custom data ?
With the standard item widgets/models you can't drag-n-drop custom item roles.
This makes sense, since the model doesn't know which UserRole+ was set.
It would need to iterate all possible item-role values when creating the drop-data.
The only solution i see is to create your own custom model and reimplement the needed drag-n-drop methods. This also give you full control over your data structure storing the data inside the model.
This is more work, but you will learn a lot and gain some performance (by avoiding the standard-item classes)