diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index 0d521fa8e55..9c3ffa81847 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -752,6 +752,19 @@ nsHTMLDocument::StartDocumentLoad(const char* aCommand,
        }
     } 
 
+    if (kCharsetFromParentFrame > charsetSource) {
+      if (dcInfo) {
+        nsCOMPtr<nsIAtom> csAtom;
+        dcInfo->GetParentCharset(getter_AddRefs(csAtom));
+        if (csAtom) {
+          csAtom->ToString(charset);
+          charsetSource = kCharsetFromParentFrame;  
+
+          // printf("### 0 >>> Having parent CS = %s\n", charset.ToNewCString());
+        }
+      }
+    }
+
     if((kCharsetFromAutoDetection > charsetSource )  && gPlugDetector)
     {
       nsCOMPtr <nsICharsetDetector> cdet = do_CreateInstance(g_detector_progid, 
diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index 091042ab2bd..f1c7fa44575 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -79,6 +79,7 @@ static NS_DEFINE_IID(kDeviceContextCID, NS_DEVICE_CONTEXT_CID);
 static NS_DEFINE_CID(kPlatformCharsetCID, NS_PLATFORMCHARSET_CID);
 static NS_DEFINE_CID(kCharsetConverterManagerCID, NS_ICHARSETCONVERTERMANAGER_CID);
 static NS_DEFINE_CID(kSimpleURICID,            NS_SIMPLEURI_CID);
+static NS_DEFINE_CID(kDocumentCharsetInfoCID, NS_DOCUMENTCHARSETINFO_CID);
 
 //*****************************************************************************
 //***    nsDocShell: Object Management
@@ -459,6 +460,14 @@ NS_IMETHODIMP nsDocShell::GetDocumentCharsetInfo(nsIDocumentCharsetInfo**
 {
    NS_ENSURE_ARG_POINTER(aDocumentCharsetInfo);
 
+  // if the mDocumentCharsetInfo does not exist already, we create it now
+  if (!mDocumentCharsetInfo) {
+    nsresult res = nsComponentManager::CreateInstance(kDocumentCharsetInfoCID, 
+      NULL, NS_GET_IID(nsIDocumentCharsetInfo), 
+      getter_AddRefs(mDocumentCharsetInfo));
+    if (NS_FAILED(res)) return NS_ERROR_FAILURE;
+  }
+
    *aDocumentCharsetInfo = mDocumentCharsetInfo;
    NS_IF_ADDREF(*aDocumentCharsetInfo);
    return NS_OK;
@@ -889,6 +898,40 @@ NS_IMETHODIMP nsDocShell::AddChild(nsIDocShellTreeItem *aChild)
          }
       }
 
+  // Now take this document's charset and set the parentCharset field of the 
+  // child's DocumentCharsetInfo to it. We'll later use that field, in the 
+  // loading process, for the charset choosing algorithm.
+  // If we fail, at any point, we just return NS_OK.
+  // This code has some performance impact. But this will be reduced when 
+  // the current charset will finally be stored as an Atom, avoiding the
+  // alias resolution extra look-up.
+
+  // we are NOT going to propagate the charset is this Chrome's docshell
+  if (mItemType == nsIDocShellTreeItem::typeChrome) return NS_OK;
+
+  nsresult res = NS_OK;
+
+  // get the child's docCSInfo object
+  nsCOMPtr<nsIDocumentCharsetInfo> dcInfo = NULL;
+  res = childAsDocShell->GetDocumentCharsetInfo(getter_AddRefs(dcInfo));
+  if (NS_FAILED(res) || (!dcInfo)) return NS_OK;
+
+  // get the parent's current charset
+  nsCOMPtr<nsIDocumentViewer> docv(do_QueryInterface(mContentViewer));
+  if (!docv) return NS_OK;
+  nsCOMPtr<nsIDocument> doc;
+  res = docv->GetDocument(*getter_AddRefs(doc));
+  if (NS_FAILED(res) || (!doc)) return NS_OK;
+  nsAutoString parentCS;
+  res = doc->GetDocumentCharacterSet(parentCS);
+  if (NS_FAILED(res)) return NS_OK;
+
+  // set the child's parentCharset
+  res = dcInfo->SetParentCharset(&parentCS);
+  if (NS_FAILED(res)) return NS_OK;
+
+  // printf("### 1 >>> Adding child. Parent CS = %s. ItemType = %d.\n", parentCS.ToNewCString(), mItemType);
+
   return NS_OK;
 }
 
diff --git a/mozilla/intl/chardet/public/nsIDocumentCharsetInfo.h b/mozilla/intl/chardet/public/nsIDocumentCharsetInfo.h
index d8583577fd6..c1ca67f9382 100644
--- a/mozilla/intl/chardet/public/nsIDocumentCharsetInfo.h
+++ b/mozilla/intl/chardet/public/nsIDocumentCharsetInfo.h
@@ -38,6 +38,8 @@
   "component://netscape/document-charset-info"
 
 // XXX doc me
+// XXX make this interface IDL
+// XXX mark the right params "const"
 
 class nsIDocumentCharsetInfo : public nsISupports 
 {
@@ -46,8 +48,19 @@ public:
 
   NS_IMETHOD SetForcedCharset(nsIAtom * aCharset) = 0;
   NS_IMETHOD GetForcedCharset(nsIAtom ** aResult) = 0;
+
   NS_IMETHOD SetForcedDetector(PRBool aForced) = 0;
   NS_IMETHOD GetForcedDetector(PRBool * aResult) = 0;
+
+  NS_IMETHOD SetParentCharset(nsIAtom * aCharset) = 0;
+  NS_IMETHOD GetParentCharset(nsIAtom ** aResult) = 0;
+
+  /**
+   * You should NOT use this method!!! It will very soon be deprecated. I only 
+   * added it here for convenience in the ongoing transition to Atoms. Use
+   * SetParentCharset(nsIAtom *) instead.
+   */
+  NS_IMETHOD SetParentCharset(nsString * aCharset) = 0;
 };
 
 #endif // nsIDocumentCharsetInfo_h__
diff --git a/mozilla/intl/chardet/src/nsDocumentCharsetInfo.cpp b/mozilla/intl/chardet/src/nsDocumentCharsetInfo.cpp
index d30d968f4b6..64d364a0bbe 100644
--- a/mozilla/intl/chardet/src/nsDocumentCharsetInfo.cpp
+++ b/mozilla/intl/chardet/src/nsDocumentCharsetInfo.cpp
@@ -21,11 +21,16 @@
  */
 
 #include "nsCharDetDll.h"
+#include "nsIServiceManager.h"
+#include "nsICharsetConverterManager.h"
+#include "nsICharsetConverterManager2.h"
 #include "nsDocumentCharsetInfo.h"
 #include "nsCOMPtr.h"
 
 // XXX doc me
 
+static NS_DEFINE_CID(kCharsetConverterManagerCID, NS_ICHARSETCONVERTERMANAGER_CID);
+
 class nsDocumentCharsetInfo : public nsIDocumentCharsetInfo
 {
   NS_DECL_ISUPPORTS
@@ -37,11 +42,17 @@ public:
 
   NS_IMETHOD SetForcedCharset(nsIAtom * aCharset);
   NS_IMETHOD GetForcedCharset(nsIAtom ** aResult);
+
   NS_IMETHOD SetForcedDetector(PRBool aForced);
   NS_IMETHOD GetForcedDetector(PRBool * aResult);
 
+  NS_IMETHOD SetParentCharset(nsIAtom * aCharset);
+  NS_IMETHOD GetParentCharset(nsIAtom ** aResult);
+  NS_IMETHOD SetParentCharset(nsString * aCharset);
+
 private:
   nsCOMPtr<nsIAtom> mForcedCharset;
+  nsCOMPtr<nsIAtom> mParentCharset;
 };
 
 class nsDocumentCharsetInfoFactory : public nsIFactory 
@@ -101,6 +112,32 @@ NS_IMETHODIMP nsDocumentCharsetInfo::GetForcedDetector(PRBool * aResult)
   return NS_OK;
 }
 
+NS_IMETHODIMP nsDocumentCharsetInfo::SetParentCharset(nsIAtom * aCharset)
+{
+  mParentCharset = aCharset;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentCharsetInfo::GetParentCharset(nsIAtom ** aResult)
+{
+  *aResult = mParentCharset;
+  if (mParentCharset) NS_ADDREF(*aResult);
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocumentCharsetInfo::SetParentCharset(nsString * aCharset)
+{
+  nsresult res = NS_OK;
+  NS_WITH_SERVICE(nsICharsetConverterManager2, ccMan, kCharsetConverterManagerCID, &res);
+  if (NS_FAILED(res)) return NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsIAtom> csAtom;
+  res = ccMan->GetCharsetAtom(aCharset->GetUnicode(), getter_AddRefs(csAtom));
+  if (NS_FAILED(res)) return NS_ERROR_FAILURE;
+
+  return SetParentCharset(csAtom);
+}
+
 NS_IMPL_ISUPPORTS(nsDocumentCharsetInfoFactory, NS_GET_IID(nsIFactory));
 
 NS_IMETHODIMP nsDocumentCharsetInfoFactory::CreateInstance(
diff --git a/mozilla/layout/html/document/src/nsHTMLDocument.cpp b/mozilla/layout/html/document/src/nsHTMLDocument.cpp
index 0d521fa8e55..9c3ffa81847 100644
--- a/mozilla/layout/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/layout/html/document/src/nsHTMLDocument.cpp
@@ -752,6 +752,19 @@ nsHTMLDocument::StartDocumentLoad(const char* aCommand,
        }
     } 
 
+    if (kCharsetFromParentFrame > charsetSource) {
+      if (dcInfo) {
+        nsCOMPtr<nsIAtom> csAtom;
+        dcInfo->GetParentCharset(getter_AddRefs(csAtom));
+        if (csAtom) {
+          csAtom->ToString(charset);
+          charsetSource = kCharsetFromParentFrame;  
+
+          // printf("### 0 >>> Having parent CS = %s\n", charset.ToNewCString());
+        }
+      }
+    }
+
     if((kCharsetFromAutoDetection > charsetSource )  && gPlugDetector)
     {
       nsCOMPtr <nsICharsetDetector> cdet = do_CreateInstance(g_detector_progid,