+/*****************************************************************************
+ * extension to NSOutlineView's interface to fix compilation warnings
+ * and let us access these 2 functions properly
+ * this uses a private Apple-API, but works fine on all current OSX releases
+ * keep checking for compatiblity with future releases though
+ *****************************************************************************/
+
+@interface NSOutlineView (UndocumentedSortImages)
++ (NSImage *)_defaultTableHeaderSortImage;
++ (NSImage *)_defaultTableHeaderReverseSortImage;
+@end
+
+