* backport my compiler warning fix when using Apple's private API

modules/gui/macosx/playlist.m

@@ -367,6 +367,18 @@
 
 @end
 
+/*****************************************************************************
+* 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 finely on all current OSX releases
+* keep checking for compatiblity with future releases though
+*****************************************************************************/
+
+@interface NSOutlineView (UndocumentedSortImages)
++ (NSImage *)_defaultTableHeaderSortImage;
++ (NSImage *)_defaultTableHeaderReverseSortImage;
+@end
+
 /*****************************************************************************
  * VLCPlaylist implementation
  *****************************************************************************/
@@ -401,26 +413,11 @@
         @"VLCPlaylistItemPboardType", nil]];
     [o_outline_view setIntercellSpacing: NSMakeSize (0.0, 1.0)];
 
-/* We need to check whether _defaultTableHeaderSortImage exists, since it 
-belongs to an Apple hidden private API, and then can "disapear" at any time*/
-
-    if( [[NSOutlineView class] respondsToSelector:@selector(_defaultTableHeaderSortImage)] )
-    {
+    /* this uses private Apple API which works fine on all releases incl. 10.4, 
+        * but keep checking in the future!
+        * These methods were added artificially to NSOutlineView's public interface above */
     o_ascendingSortingImage = [[NSOutlineView class] _defaultTableHeaderSortImage];
-    }
-    else
-    {
-        o_ascendingSortingImage = nil;
-    }
-
-    if( [[NSOutlineView class] respondsToSelector:@selector(_defaultTableHeaderReverseSortImage)] )
-    {
     o_descendingSortingImage = [[NSOutlineView class] _defaultTableHeaderReverseSortImage];
-    }
-    else
-    {
-        o_descendingSortingImage = nil;
-    }
 
     o_tc_sortColumn = nil;