A drag-and-drop operation in a graphical user interface is controlled dependence upon whether the destination for the operation is a content object or a service object. If the destination of a drag-and-drop operation is a content object, the resulting action is to move the dragged object from its original...http://www.google.de/patents/US6535230?utm_source=gb-gplus-sharePatent US6535230 - Graphical user interface providing consistent behavior for the dragging and dropping of content objects
