Added verticalMargin accessor to CPCollectionView.

AppKit/CPCollectionView.j

@@ -559,6 +559,11 @@
 
 // Cappuccino Additions
 
+/*!
+    Sets the collection view's vertical spacing between elements.
+    @param aVerticalMargin the number of pixels to place between elements
+*/
+
 - (void)setVerticalMargin:(float)aVerticalMargin
 {
     if (_verticalMargin == aVerticalMargin)
@@ -569,6 +574,15 @@
     [self tile];
 }
 
+/*!
+    Gets the collection view's current vertical spacing between elements.
+*/
+
+- (float)verticalMargin
+{
+    return _verticalMargin;
+}
+
 /*!
     Sets the collection view's delegate
     @param aDelegate the new delegate