diff --git a/mozilla/modules/plugin/base/public/npapi.h b/mozilla/modules/plugin/base/public/npapi.h
index 4f8add67060..2a721d75b65 100644
--- a/mozilla/modules/plugin/base/public/npapi.h
+++ b/mozilla/modules/plugin/base/public/npapi.h
@@ -38,7 +38,7 @@
 
 
 /*
- *  npapi.h $Revision: 3.26 $
+ *  npapi.h $Revision: 3.27 $
  *  Netscape client plug-in API spec
  */
 
@@ -321,6 +321,49 @@ typedef struct
 
 #endif /* XP_UNIX */
 
+
+/*
+ *   The following masks are applied on certain platforms to NPNV and 
+ *   NPPV selectors that pass around pointers to COM interfaces. Newer 
+ *   compilers on some platforms may generate vtables that are not 
+ *   compatible with older compilers. To prevent older plugins from 
+ *   not understanding a new browser's ABI, these masks change the 
+ *   values of those selectors on those platforms. To remain backwards
+ *   compatible with differenet versions of the browser, plugins can 
+ *   use these masks to dynamically determine and use the correct C++
+ *   ABI that the browser is expecting. This does not apply to Windows 
+ *   as Microsoft's COM ABI will likely not change.
+ */
+
+#define NP_ABI_GCC3_MASK  0x10000000
+/*
+ *   gcc 3.x generated vtables on UNIX and OSX are incompatible with 
+ *   previous compilers.
+ */
+#if (defined (XP_UNIX) && defined(__GNUC__) && (__GNUC__ >= 3))
+#define _NP_ABI_MIXIN_FOR_GCC3 NP_ABI_GCC3_MASK
+#else
+#define _NP_ABI_MIXIN_FOR_GCC3 0
+#endif
+
+
+#define NP_ABI_MACHO_MASK 0x01000000
+/*
+ *   On OSX, the Mach-O executable format is significantly
+ *   different than CFM. In addition to having a different
+ *   C++ ABI, it also has has different C calling convention.
+ *   You must use glue code when calling between CFM and
+ *   Mach-O C functions. 
+ */
+#if (defined(TARGET_RT_MAC_MACHO))
+#define _NP_ABI_MIXIN_FOR_MACHO NP_ABI_MACHO_MASK
+#else
+#define _NP_ABI_MIXIN_FOR_MACHO 0
+#endif
+
+
+#define NP_ABI_MASK (_NP_ABI_MIXIN_FOR_GCC3 | _NP_ABI_MIXIN_FOR_MACHO)
+
 /*
  * List of variable names for which NPP_GetValue shall be implemented
  */
@@ -333,7 +376,7 @@ typedef enum {
   NPPVpluginWindowSize,
   NPPVpluginTimerInterval,
 
-  NPPVpluginScriptableInstance = 10,
+  NPPVpluginScriptableInstance = (10 | NP_ABI_MASK),
   NPPVpluginScriptableIID = 11,
 
   /* 12 and over are available on Mozilla builds starting with 0.9.9 */
@@ -353,9 +396,9 @@ typedef enum {
   NPNVisOfflineBool,
 
   /* 10 and over are available on Mozilla builds starting with 0.9.4 */
-  NPNVserviceManager = 10,
-  NPNVDOMElement     = 11,   /* available in Mozilla 1.2 */
-  NPNVDOMWindow      = 12
+  NPNVserviceManager = (10 | NP_ABI_MASK),
+  NPNVDOMElement     = (11 | NP_ABI_MASK),   /* available in Mozilla 1.2 */
+  NPNVDOMWindow      = (12 | NP_ABI_MASK)
 } NPNVariable;
 
 /*
diff --git a/mozilla/modules/plugin/base/src/ns4xPluginInstance.cpp b/mozilla/modules/plugin/base/src/ns4xPluginInstance.cpp
index 6682389421a..e5cb66c1333 100644
--- a/mozilla/modules/plugin/base/src/ns4xPluginInstance.cpp
+++ b/mozilla/modules/plugin/base/src/ns4xPluginInstance.cpp
@@ -1165,6 +1165,25 @@ NS_IMETHODIMP ns4xPluginInstance::HandleEvent(nsPluginEvent* event, PRBool* hand
   return NS_OK;
 }
 
+nsresult ns4xPluginInstance::GetValueInternal(NPPVariable variable, void* value)
+{
+  nsresult  res = NS_OK;
+  if(fCallbacks->getvalue && mStarted) {
+
+    NS_TRY_SAFE_CALL_RETURN(res, 
+                            CallNPP_GetValueProc(fCallbacks->getvalue, 
+                                                 &fNPP, 
+                                                 variable, 
+                                                 value), 
+                                                 fLibrary, this);
+    NPP_PLUGIN_LOG(PLUGIN_LOG_NORMAL,
+    ("NPP GetValue called: this=%p, npp=%p, var=%d, value=%d, return=%d\n", 
+    this, &fNPP, variable, value, res));
+  }
+
+  return res;
+}
+
 
 ////////////////////////////////////////////////////////////////////////
 NS_IMETHODIMP ns4xPluginInstance :: GetValue(nsPluginInstanceVariable variable,
@@ -1190,17 +1209,7 @@ NS_IMETHODIMP ns4xPluginInstance :: GetValue(nsPluginInstanceVariable variable,
       break;
 
     default:
-      if(fCallbacks->getvalue && mStarted) {
-        NS_TRY_SAFE_CALL_RETURN(res, 
-                                CallNPP_GetValueProc(fCallbacks->getvalue, 
-                                                     &fNPP, 
-                                                     (NPPVariable)variable, 
-                                                     value), 
-                                                     fLibrary, this);
-        NPP_PLUGIN_LOG(PLUGIN_LOG_NORMAL,
-        ("NPP GetValue called: this=%p, npp=%p, var=%d, value=%d, return=%d\n", 
-        this, &fNPP, variable, value, res));
-      }
+      res = GetValueInternal((NPPVariable)variable, value);
   }
 
   return res;
@@ -1254,7 +1263,7 @@ NS_IMETHODIMP ns4xPluginInstance :: GetScriptablePeer(void * *aScriptablePeer)
     return NS_ERROR_NULL_POINTER;
 
   *aScriptablePeer = nsnull;
-  return GetValue(nsPluginInstanceVariable_ScriptableInstance, aScriptablePeer);
+  return GetValueInternal(NPPVpluginScriptableInstance, aScriptablePeer);
 }
 
 
@@ -1262,13 +1271,9 @@ NS_IMETHODIMP ns4xPluginInstance :: GetScriptablePeer(void * *aScriptablePeer)
 /* readonly attribute nsIIDPtr scriptableInterface; */
 NS_IMETHODIMP ns4xPluginInstance :: GetScriptableInterface(nsIID * *aScriptableInterface)
 {
-#if !defined(XP_MACOSX) // Workaround suspected bug
   if (!aScriptableInterface)
     return NS_ERROR_NULL_POINTER;
 
   *aScriptableInterface = nsnull;
-  return GetValue(nsPluginInstanceVariable_ScriptableIID, (void*)aScriptableInterface);
-#else
-  return NS_ERROR_NOT_IMPLEMENTED;
-#endif
+  return GetValueInternal(NPPVpluginScriptableIID, (void*)aScriptableInterface);
 }
diff --git a/mozilla/modules/plugin/base/src/ns4xPluginInstance.h b/mozilla/modules/plugin/base/src/ns4xPluginInstance.h
index 36567df8c8b..550c08465a9 100644
--- a/mozilla/modules/plugin/base/src/ns4xPluginInstance.h
+++ b/mozilla/modules/plugin/base/src/ns4xPluginInstance.h
@@ -161,6 +161,11 @@ public:
 protected:
 
     nsresult InitializePlugin(nsIPluginInstancePeer* peer);
+
+    /**
+     * Calls NPP_GetValue
+     */
+    nsresult GetValueInternal(NPPVariable variable, void* value);
     
     /**
      * The plugin instance peer for this instance.