use alternating row bg colors in outliner on panther to make it easier to read

git-svn-id: svn://10.0.0.236/trunk@156281 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/camino/src/bookmarks/BookmarkOutlineView.mm

@@ -51,6 +51,11 @@
 - (void)awakeFromNib
 {
   [self registerForDraggedTypes:[NSArray arrayWithObjects:@"MozURLType", @"MozBookmarkType", NSStringPboardType, NSURLPboardType, nil]];
+
+  // on panther and later, use the alternating row bg color to make the table
+  // easier to read
+  if ([self respondsToSelector:@selector(setUsesAlternatingRowBackgroundColors:)])
+    [self setUsesAlternatingRowBackgroundColors:YES];
 }
 
 -(NSMenu*)menu