and the include file it will need

mailnews/news/src/nsNewsFolder.cpp

@@ -69,6 +69,8 @@
 #include "nsINetSupportDialogService.h"
 #include "nsIInterfaceRequestor.h"
 
+#include "nsReadableUtils.h"
+
 // we need this because of an egcs 1.0 (and possibly gcc) compiler bug
 // that doesn't allow you to call ::nsISupports::GetIID() inside of a class
 // that multiply inherits from nsISupports