diff --git a/mozilla/gfx/public/nsDeviceContext.h b/mozilla/gfx/public/nsDeviceContext.h
index 26d5a47ab8c..bd229d07fcd 100644
--- a/mozilla/gfx/public/nsDeviceContext.h
+++ b/mozilla/gfx/public/nsDeviceContext.h
@@ -80,7 +80,7 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_GFX DeviceContextImpl : public nsIDeviceContext,
                                  public nsIObserver,
@@ -185,6 +185,6 @@ public:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif /* nsDeviceContext_h___ */
diff --git a/mozilla/gfx/src/nsPrintOptionsImpl.h b/mozilla/gfx/src/nsPrintOptionsImpl.h
index 1b59c6d8306..7a8112839b8 100644
--- a/mozilla/gfx/src/nsPrintOptionsImpl.h
+++ b/mozilla/gfx/src/nsPrintOptionsImpl.h
@@ -32,7 +32,7 @@
 //class nsIPrintSettings;
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 //*****************************************************************************
 //***    nsPrintOptions
@@ -80,6 +80,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif /* nsPrintOptions_h__ */
diff --git a/mozilla/gfx/src/nsPrintSession.h b/mozilla/gfx/src/nsPrintSession.h
index 48d58bff7fa..4b0f43e99ef 100644
--- a/mozilla/gfx/src/nsPrintSession.h
+++ b/mozilla/gfx/src/nsPrintSession.h
@@ -49,7 +49,7 @@
 //*****************************************************************************
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_GFX nsPrintSession : public nsIPrintSession,
                               public nsSupportsWeakReference
@@ -65,6 +65,6 @@ public:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif // nsPrintSession_h__
diff --git a/mozilla/gfx/src/nsPrintSettingsImpl.h b/mozilla/gfx/src/nsPrintSettingsImpl.h
index e149374c344..25e96258e29 100644
--- a/mozilla/gfx/src/nsPrintSettingsImpl.h
+++ b/mozilla/gfx/src/nsPrintSettingsImpl.h
@@ -35,7 +35,7 @@
 //*****************************************************************************
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_GFX nsPrintSettings : public nsIPrintSettings
 {
@@ -116,6 +116,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif /* nsPrintSettings_h__ */
diff --git a/mozilla/gfx/src/nsRenderingContextImpl.h b/mozilla/gfx/src/nsRenderingContextImpl.h
index 29c333c75cf..67081e01aa4 100644
--- a/mozilla/gfx/src/nsRenderingContextImpl.h
+++ b/mozilla/gfx/src/nsRenderingContextImpl.h
@@ -52,7 +52,7 @@ typedef struct {
 } Edge;
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class nsRenderingContextImpl : public nsIRenderingContext
 {
@@ -211,7 +211,7 @@ private:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 /** ---------------------------------------------------
  *  Class QBezierCurve, a quadratic bezier curve
diff --git a/mozilla/mailnews/base/util/nsMsgDBFolder.h b/mozilla/mailnews/base/util/nsMsgDBFolder.h
index dbc26a0edb7..0f0d5322246 100644
--- a/mozilla/mailnews/base/util/nsMsgDBFolder.h
+++ b/mozilla/mailnews/base/util/nsMsgDBFolder.h
@@ -66,7 +66,7 @@ class nsICollation;
   */ 
 
 #undef IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_MSG_BASE nsMsgDBFolder: public nsRDFResource,
                                  public nsSupportsWeakReference,
@@ -251,6 +251,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif
diff --git a/mozilla/mailnews/base/util/nsMsgIncomingServer.h b/mozilla/mailnews/base/util/nsMsgIncomingServer.h
index d05515bc0fc..928276ba492 100644
--- a/mozilla/mailnews/base/util/nsMsgIncomingServer.h
+++ b/mozilla/mailnews/base/util/nsMsgIncomingServer.h
@@ -62,7 +62,7 @@ class nsIMsgProtocolInfo;
  */
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_MSG_BASE nsMsgIncomingServer : public nsIMsgIncomingServer,
                                         public nsSupportsWeakReference
@@ -116,6 +116,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif // nsMsgIncomingServer_h__
diff --git a/mozilla/mailnews/base/util/nsMsgMailNewsUrl.h b/mozilla/mailnews/base/util/nsMsgMailNewsUrl.h
index ab8b5074714..1d776d6a25b 100644
--- a/mozilla/mailnews/base/util/nsMsgMailNewsUrl.h
+++ b/mozilla/mailnews/base/util/nsMsgMailNewsUrl.h
@@ -63,7 +63,7 @@
 //////////////////////////////////////////////////////////////////////////////////
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_MSG_BASE nsMsgMailNewsUrl : public nsIMsgMailNewsUrl
 {
@@ -110,6 +110,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif /* nsMsgMailNewsUrl_h___ */
diff --git a/mozilla/mailnews/base/util/nsMsgProtocol.h b/mozilla/mailnews/base/util/nsMsgProtocol.h
index 09510f8bc2c..45a80b63f5e 100644
--- a/mozilla/mailnews/base/util/nsMsgProtocol.h
+++ b/mozilla/mailnews/base/util/nsMsgProtocol.h
@@ -65,7 +65,7 @@ class nsMsgFilePostHelper;
 class nsIProxyInfo;
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 // This is a helper class used to encapsulate code shared between all of the
 // mailnews protocol objects (imap, news, pop, smtp, etc.) In particular,
@@ -254,6 +254,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif /* nsMsgProtocol_h__ */
diff --git a/mozilla/mailnews/base/util/nsMsgTxn.h b/mozilla/mailnews/base/util/nsMsgTxn.h
index cd1ce48d876..0f8355cd979 100644
--- a/mozilla/mailnews/base/util/nsMsgTxn.h
+++ b/mozilla/mailnews/base/util/nsMsgTxn.h
@@ -52,7 +52,7 @@
  */
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_MSG_BASE nsMsgTxn : public nsITransaction
 {
@@ -83,6 +83,6 @@ protected:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif
diff --git a/mozilla/xpcom/base/nscore.h b/mozilla/xpcom/base/nscore.h
index 6addc519569..dbc355932ce 100644
--- a/mozilla/xpcom/base/nscore.h
+++ b/mozilla/xpcom/base/nscore.h
@@ -81,34 +81,40 @@
  * wrap your class as follows:
  *
  * #undef  IMETHOD_VISIBILITY
- * #define IMETHOD_VISIBILITY default
-
+ * #define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
+ *
  * class Foo {
  * ...
  * };
  *
  * #undef  IMETHOD_VISIBILITY
- * #define IMETHOD_VISIBILITY hidden
+ * #define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
  *
  * Don't forget to change the visibility back to hidden before the end
  * of a header!
+ *
+ * Other examples:
+ *
+ * NS_HIDDEN_(int) someMethod();
+ * SomeCtor() NS_HIDDEN;
  */
 
-#ifdef HAVE_VISIBILITY_ATTRIBUTE_notyet
-#define NS_VISIBILITY_(vis) __attribute__ ((visibility (#vis)))
-#define NS_HIDDEN_(type)   type NS_VISIBILITY(hidden)
+#ifdef HAVE_VISIBILITY_ATTRIBUTE
+#define NS_VISIBILITY_HIDDEN   __attribute__ ((visibility ("hidden")))
+#define NS_VISIBILITY_DEFAULT
+
+#define NS_HIDDEN_(type)   type NS_VISIBILITY_HIDDEN
 #else
-#define NS_VISIBILITY_(vis)
+#define NS_VISIBILITY_HIDDEN
+#define NS_VISIBILITY_DEFAULT
+
 #define NS_HIDDEN_(type)   type
 #endif
 
-#define NS_HIDDEN NS_VISIBILITY(hidden)
+#define NS_HIDDEN           NS_VISIBILITY_HIDDEN
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY  hidden
-/* Extra layer of macro expansion to allow IMETHOD_VISIBILITY to be
-   stringified. */
-#define NS_VISIBILITY(vis) NS_VISIBILITY_(vis)
+#define IMETHOD_VISIBILITY  NS_VISIBILITY_HIDDEN
 
 #ifdef NS_WIN32
 
@@ -140,7 +146,7 @@
 #define NS_IMPORT_(type) type
 #define NS_EXPORT
 #define NS_EXPORT_(type) type
-#define NS_IMETHOD_(type) virtual type NS_VISIBILITY(IMETHOD_VISIBILITY)
+#define NS_IMETHOD_(type) virtual type IMETHOD_VISIBILITY
 #define NS_IMETHODIMP_(type) type
 #define NS_METHOD_(type) type
 #define NS_CALLBACK_(_type, _name) _type (* _name)
diff --git a/mozilla/xpcom/ds/nsSupportsArray.h b/mozilla/xpcom/ds/nsSupportsArray.h
index 652246d7641..69efcdbdf2a 100644
--- a/mozilla/xpcom/ds/nsSupportsArray.h
+++ b/mozilla/xpcom/ds/nsSupportsArray.h
@@ -45,7 +45,7 @@
 static const PRUint32 kAutoArraySize = 8;
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_COM nsSupportsArray : public nsISupportsArray {
 public:
@@ -167,6 +167,6 @@ private:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 #endif // nsSupportsArray_h__
diff --git a/mozilla/xpcom/glue/nsWeakReference.h b/mozilla/xpcom/glue/nsWeakReference.h
index 2fcd2df7718..cc8a6316b79 100644
--- a/mozilla/xpcom/glue/nsWeakReference.h
+++ b/mozilla/xpcom/glue/nsWeakReference.h
@@ -30,7 +30,7 @@
 class nsWeakReference;
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class NS_COM nsSupportsWeakReference : public nsISupportsWeakReference
   {
@@ -65,7 +65,7 @@ class NS_COM nsSupportsWeakReference : public nsISupportsWeakReference
   };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 class NS_COM nsWeakReference : public nsIWeakReference
   {
diff --git a/mozilla/xpcom/reflect/xptcall/public/xptcall.h b/mozilla/xpcom/reflect/xptcall/public/xptcall.h
index 5983180fdc1..eb5f631834f 100644
--- a/mozilla/xpcom/reflect/xptcall/public/xptcall.h
+++ b/mozilla/xpcom/reflect/xptcall/public/xptcall.h
@@ -187,7 +187,7 @@ struct nsXPTCVariant : public nsXPTCMiniVariant
 /***************************************************************************/
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY default
+#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
 
 class nsXPTCStubBase : public nsISupports
 {
@@ -215,7 +215,7 @@ public:
 };
 
 #undef  IMETHOD_VISIBILITY
-#define IMETHOD_VISIBILITY hidden
+#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
 
 PR_BEGIN_EXTERN_C