Question: How do I get mouse position changes during a drag and drop operation in a table view ?
Answer: The following method is called whenever the drag destination changes to a different row in the table view: See http://developer.apple.com/documentation/Cocoa/Conceptual/TableView/Tasks/UsingDragAndDrop.html
A more general technique that works for all views is the following: -draggingUpdated: http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/ObjC_classic/Protocols/NSDraggingDestination.html
-draggingUpdated: is part of an informal protocol. Informal protocols are described here: http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC/LanguageOverview/chapter_3_section_7.html