startDrag and dropOn

startDrag(src_objectOrName, sx, sy)

This function performs a start drag operation. It initiates a drag on the source_objectOrName widget starting at position sx and sy (in the source_objectOrName widget's coordinates). This can be useful if the drop target object becomes available only after the drag starts.

dropOn(target_objectOrName, tx, ty)

This function performs a drop operation. It drops the dragged object on the target_objectOrName widget at position tx and ty (in the target_objectOrName widget's coordinates). This function should only be called after startDrag has been called, i.e., a drag operation is in progress.