Implement this method to enable dragging onto the control.
- macOS 10.5+
The path control that sent the message.
An object containing details about this dragging operation.
This method is called when something is dragged over the control. Return
NSDrag to refuse the drop, or return anything else to accept it.
If not implemented, and the control's cell is editable, the drop is accepted if it contains an
NSFilenames that conforms to the cell’s allowed types. Implementation of this method is optional.