I have successfully implemented a drag and drop operation in GTK4/Python where the user drags an item from a toolbox onto a canvas by implementing a DragSource and DropTarget To improve this I need to be able to do the following whilst dragging

1. Modify or redraw the custom icon I initiate in drag-prepare
2. Lock the pointer movement to a snap grid on the canvas. The drag motion will cause the pointer to jump between snap grid points.

Is there any way I can modify these items ion the fly?

I have looked through the GTK4 documentation and can see nothing which would allow me to do this during the drag motion phase.