CPCollectionView Implemented - (CPView)draggingViewForItemsAtIndexes:(CPIndexSet)indexes withEvent:(CPEvent)event offset:(CGPoint)dragImageOffset

and the corresponding delegate method from where you can ask for the default dragged view. Multiple selection not implemented yet.

AppKit/CPCollectionView.j

@@ -695,26 +695,37 @@
     var dragTypes = [_delegate collectionView:self dragTypesForItemsAtIndexes:_selectionIndexes];
 
     [[CPPasteboard pasteboardWithName:CPDragPboard] declareTypes:dragTypes owner:self];
-
-    if (!_itemForDragging)
-        _itemForDragging = [self newItemForRepresentedObject:_content[[_selectionIndexes firstIndex]]];
+    
+    var dragImageOffset = CGSizeMakeZero(),
+        view;
+        
+    if ([_delegate respondsToSelector:@selector(collectionView:draggingViewForItemsAtIndexes:withEvent:offset:)])
+        view = [_delegate collectionView:self draggingViewForItemsAtIndexes:_selectionIndexes withEvent:_mouseDownEvent offset:dragImageOffset];
     else
-        [_itemForDragging setRepresentedObject:_content[[_selectionIndexes firstIndex]]];
-
-    var view = [_itemForDragging view];
+        view = [self draggingViewForItemsAtIndexes:_selectionIndexes withEvent:_mouseDownEvent offset:dragImageOffset];
 
     [view setFrameSize:_itemSize];
     [view setAlphaValue:0.7];
 
     [self dragView:view
         at:[[_items[[_selectionIndexes firstIndex]] view] frame].origin
-        offset:CGSizeMakeZero()
+        offset:dragImageOffset
         event:_mouseDownEvent
         pasteboard:nil
         source:self
         slideBack:YES];
 }
 
+- (CPView)draggingViewForItemsAtIndexes:(CPIndexSet)indexes withEvent:(CPEvent)event offset:(CGPoint)dragImageOffset
+{
+    if (!_itemForDragging)
+        _itemForDragging = [self newItemForRepresentedObject:_content[0]];
+    else
+        [_itemForDragging setRepresentedObject:_content[[indexes firstIndex]]];
+        
+    return [_itemForDragging view];
+}
+
 /*!
     Places the selected items on the specified pasteboard. The items are requested from the collection's delegate.
     @param aPasteboard the pasteboard to put the items on