A value from the DROPEFFECT enumerated type, which indicates the type of drop that would occur if the user dropped the object at this position. The type of drop usually depends on the current key state indicated by dwKeyState. A standard mapping of keystates to DROPEFFECT values is:
DROPEFFECT_NONE The data object cannot be dropped in this window.
DROPEFFECT_LINK for MK_CONTROL | MK_SHIFT Creates a linkage between the object and its server.
DROPEFFECT_COPY for MK_CONTROL Creates a copy of the dropped object.
DROPEFFECT_MOVE for MK_ALT Creates a copy of the dropped object and delete the original object.
DROPEFFECT_SCROLL Indicates that a drag scroll operation is about to occur or is occurring in the target view.
For more information, see the MFC Advanced Concepts sample OCLIENT.
Override this function when you want to provide special behavior for this event. The default implementation automatically scrolls windows when the cursor is dragged into the default scroll region inside the border of each window.For more information, see the article Drag and Drop: Implementing a Drop Target.