diff --git a/mozilla/embedding/components/ui/helperAppDlg/nsHelperAppDlg.js b/mozilla/embedding/components/ui/helperAppDlg/nsHelperAppDlg.js
index 7c8f5d0c7c4..72ac3c7548f 100644
--- a/mozilla/embedding/components/ui/helperAppDlg/nsHelperAppDlg.js
+++ b/mozilla/embedding/components/ui/helperAppDlg/nsHelperAppDlg.js
@@ -126,6 +126,15 @@ nsHelperAppDialog.prototype = {
                         .getInterface( Components.interfaces.nsIDOMWindowInternal );
         picker.init( parent, windowTitle, nsIFilePicker.modeSave );
         picker.defaultString = aDefaultFile;
+        if (aSuggestedFileExtension) {
+            // aSuggestedFileExtension includes the period, so strip it
+            picker.defaultExtension = aSuggestedFileExtension.substring(1);
+        } else {
+            try {
+                picker.defaultExtension = this.mLauncher.MIMEInfo.primaryExtension;
+            } catch (ex) {
+            }
+        }
 
         var wildCardExtension = "*";
         if ( aSuggestedFileExtension ) {
diff --git a/mozilla/uriloader/exthandler/nsExternalHelperAppService.cpp b/mozilla/uriloader/exthandler/nsExternalHelperAppService.cpp
index 6924487d8c6..a8b0c726335 100644
--- a/mozilla/uriloader/exthandler/nsExternalHelperAppService.cpp
+++ b/mozilla/uriloader/exthandler/nsExternalHelperAppService.cpp
@@ -93,7 +93,7 @@ static PRBool PR_CALLBACK DeleteEntry(nsHashKey *aKey, void *aData, void* closur
 static nsDefaultMimeTypeEntry defaultMimeEntries [] = 
 {
   { TEXT_PLAIN, "txt,text", "Text File", 'TEXT', 'ttxt' },
-  { TEXT_HTML, "htm,html,shtml,ehtml", "HyperText Markup Language", 'TEXT', 'MOSS' },
+  { TEXT_HTML, "html,htm,shtml,ehtml", "HyperText Markup Language", 'TEXT', 'MOSS' },
   { TEXT_RDF, "rdf", "Resource Description Framework", 'TEXT','ttxt' },
   { TEXT_XUL, "xul", "XML-Based User Interface Language", 'TEXT', 'ttxt' },
   { TEXT_XML,          "xml,xsl,xbl", "Extensible Markup Language", 'TEXT', 'ttxt' },
diff --git a/mozilla/widget/public/nsIFilePicker.idl b/mozilla/widget/public/nsIFilePicker.idl
index 812826bd2d7..43318809fb2 100644
--- a/mozilla/widget/public/nsIFilePicker.idl
+++ b/mozilla/widget/public/nsIFilePicker.idl
@@ -73,9 +73,20 @@ interface nsIFilePicker : nsISupports
   void appendFilter(in wstring title,
                     in wstring filter);
 
-  /* what is this? */
+ /**
+  * The filename that should be suggested to the user as a default.
+  *
+  * @throws NS_ERROR_FAILURE on attempts to get
+  */
   attribute wstring defaultString;
 
+ /**
+  * The extension that should be associated with files of the type we
+  * want to work with.  On some platforms, this extension will be
+  * automatically appended to filenames the user enters, if needed.  
+  */
+  attribute wstring defaultExtension;
+  
  /**
   * The filter which is currently selected in the File Picker dialog
   *
diff --git a/mozilla/widget/src/beos/nsFilePicker.cpp b/mozilla/widget/src/beos/nsFilePicker.cpp
index ba7441e94c3..523b06e9ce4 100644
--- a/mozilla/widget/src/beos/nsFilePicker.cpp
+++ b/mozilla/widget/src/beos/nsFilePicker.cpp
@@ -257,6 +257,22 @@ NS_IMETHODIMP nsFilePicker::GetDefaultString(PRUnichar **aString)
   return NS_ERROR_FAILURE;
 }
 
+//-------------------------------------------------------------------------
+//
+// The default extension to use for files
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsFilePicker::GetDefaultExtension(PRUnichar **aExtension)
+{
+  *aExtension = nsnull;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const PRUnichar *aExtension)
+{
+  return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Set the display directory
diff --git a/mozilla/widget/src/beos/nsFilePicker.h b/mozilla/widget/src/beos/nsFilePicker.h
index 3c210c8100d..a28632e0120 100644
--- a/mozilla/widget/src/beos/nsFilePicker.h
+++ b/mozilla/widget/src/beos/nsFilePicker.h
@@ -50,6 +50,8 @@ public:
   // nsIFilePicker (less what's in nsBaseFilePicker)
   NS_IMETHOD GetDefaultString(PRUnichar * *aDefaultString);
   NS_IMETHOD SetDefaultString(const PRUnichar * aDefaultString);
+  NS_IMETHOD GetDefaultExtension(PRUnichar * *aDefaultExtension);
+  NS_IMETHOD SetDefaultExtension(const PRUnichar * aDefaultExtension);
   NS_IMETHOD GetDisplayDirectory(nsILocalFile * *aDisplayDirectory);
   NS_IMETHOD SetDisplayDirectory(nsILocalFile * aDisplayDirectory);
   NS_IMETHOD GetFile(nsILocalFile * *aFile);
diff --git a/mozilla/widget/src/cocoa/nsFilePicker.cpp b/mozilla/widget/src/cocoa/nsFilePicker.cpp
index cc9eb1badc7..aa271599f58 100644
--- a/mozilla/widget/src/cocoa/nsFilePicker.cpp
+++ b/mozilla/widget/src/cocoa/nsFilePicker.cpp
@@ -699,6 +699,22 @@ NS_IMETHODIMP nsFilePicker::GetDefaultString(PRUnichar **aString)
   return NS_ERROR_FAILURE;
 }
 
+//-------------------------------------------------------------------------
+//
+// The default extension to use for files
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsFilePicker::GetDefaultExtension(PRUnichar **aExtension)
+{
+  *aExtension = nsnull;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const PRUnichar *aExtension)
+{
+  return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Set the display directory
diff --git a/mozilla/widget/src/cocoa/nsFilePicker.h b/mozilla/widget/src/cocoa/nsFilePicker.h
index d908d9b45ae..52073c8f2d6 100644
--- a/mozilla/widget/src/cocoa/nsFilePicker.h
+++ b/mozilla/widget/src/cocoa/nsFilePicker.h
@@ -48,6 +48,8 @@ public:
     // nsIFilePicker (less what's in nsBaseFilePicker)
   NS_IMETHOD GetDefaultString(PRUnichar * *aDefaultString);
   NS_IMETHOD SetDefaultString(const PRUnichar * aDefaultString);
+  NS_IMETHOD GetDefaultExtension(PRUnichar * *aDefaultExtension);
+  NS_IMETHOD SetDefaultExtension(const PRUnichar * aDefaultExtension);
   NS_IMETHOD GetDisplayDirectory(nsILocalFile * *aDisplayDirectory);
   NS_IMETHOD SetDisplayDirectory(nsILocalFile * aDisplayDirectory);
   NS_IMETHOD GetFile(nsILocalFile * *aFile);
diff --git a/mozilla/widget/src/mac/nsFilePicker.cpp b/mozilla/widget/src/mac/nsFilePicker.cpp
index 58aa4e9cee0..bd4b24de108 100644
--- a/mozilla/widget/src/mac/nsFilePicker.cpp
+++ b/mozilla/widget/src/mac/nsFilePicker.cpp
@@ -932,6 +932,22 @@ NS_IMETHODIMP nsFilePicker::GetDefaultString(PRUnichar **aString)
   return NS_ERROR_FAILURE;
 }
 
+//-------------------------------------------------------------------------
+//
+// The default extension to use for files
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsFilePicker::GetDefaultExtension(PRUnichar **aExtension)
+{
+  *aExtension = nsnull;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const PRUnichar *aExtension)
+{
+  return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Set the display directory
diff --git a/mozilla/widget/src/mac/nsFilePicker.h b/mozilla/widget/src/mac/nsFilePicker.h
index d52770274ef..2fadd203c41 100644
--- a/mozilla/widget/src/mac/nsFilePicker.h
+++ b/mozilla/widget/src/mac/nsFilePicker.h
@@ -48,6 +48,8 @@ public:
     // nsIFilePicker (less what's in nsBaseFilePicker)
   NS_IMETHOD GetDefaultString(PRUnichar * *aDefaultString);
   NS_IMETHOD SetDefaultString(const PRUnichar * aDefaultString);
+  NS_IMETHOD GetDefaultExtension(PRUnichar * *aDefaultExtension);
+  NS_IMETHOD SetDefaultExtension(const PRUnichar * aDefaultExtension);
   NS_IMETHOD GetDisplayDirectory(nsILocalFile * *aDisplayDirectory);
   NS_IMETHOD SetDisplayDirectory(nsILocalFile * aDisplayDirectory);
   NS_IMETHOD GetFile(nsILocalFile * *aFile);
diff --git a/mozilla/widget/src/os2/nsFilePicker.cpp b/mozilla/widget/src/os2/nsFilePicker.cpp
index f063b3d05f5..d1a6689b76d 100644
--- a/mozilla/widget/src/os2/nsFilePicker.cpp
+++ b/mozilla/widget/src/os2/nsFilePicker.cpp
@@ -325,6 +325,22 @@ NS_IMETHODIMP nsFilePicker::GetDefaultString(PRUnichar **aString)
   return NS_ERROR_FAILURE;
 }
 
+//-------------------------------------------------------------------------
+//
+// The default extension to use for files
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsFilePicker::GetDefaultExtension(PRUnichar **aExtension)
+{
+  *aExtension = nsnull;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const PRUnichar *aExtension)
+{
+  return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Set the display directory
diff --git a/mozilla/widget/src/os2/nsFilePicker.h b/mozilla/widget/src/os2/nsFilePicker.h
index 95a2a47af3a..41a119bd42a 100644
--- a/mozilla/widget/src/os2/nsFilePicker.h
+++ b/mozilla/widget/src/os2/nsFilePicker.h
@@ -47,6 +47,8 @@ public:
     // nsIFilePicker (less what's in nsBaseFilePicker)
   NS_IMETHOD GetDefaultString(PRUnichar * *aDefaultString);
   NS_IMETHOD SetDefaultString(const PRUnichar * aDefaultString);
+  NS_IMETHOD GetDefaultExtension(PRUnichar * *aDefaultExtension);
+  NS_IMETHOD SetDefaultExtension(const PRUnichar * aDefaultExtension);
   NS_IMETHOD GetDisplayDirectory(nsILocalFile * *aDisplayDirectory);
   NS_IMETHOD SetDisplayDirectory(nsILocalFile * aDisplayDirectory);
   NS_IMETHOD GetFile(nsILocalFile * *aFile);
diff --git a/mozilla/widget/src/windows/nsFilePicker.cpp b/mozilla/widget/src/windows/nsFilePicker.cpp
index 94820e9e445..42cd4d03b4b 100644
--- a/mozilla/widget/src/windows/nsFilePicker.cpp
+++ b/mozilla/widget/src/windows/nsFilePicker.cpp
@@ -44,6 +44,8 @@ NS_IMPL_ISUPPORTS1(nsFilePicker, nsIFilePicker)
 
 char nsFilePicker::mLastUsedDirectory[MAX_PATH+1] = { 0 };
 
+#define MAX_EXTENSION_LENGTH 10
+
 //-------------------------------------------------------------------------
 //
 // nsFilePicker constructor
@@ -147,6 +149,8 @@ NS_IMETHODIMP nsFilePicker::Show(PRInt16 *retval)
 
     ofn.lStructSize = sizeof(ofn);
 
+    char extensionBuffer[MAX_EXTENSION_LENGTH+1] = "";
+    
     PRInt32 l = (mFilterList.Length()+2)*2;
     char *filterBuffer = (char*) nsMemory::Alloc(l);
     int len = WideCharToMultiByte(CP_ACP, 0,
@@ -160,7 +164,7 @@ NS_IMETHODIMP nsFilePicker::Show(PRInt16 *retval)
     if (initialDir && *initialDir) {
       ofn.lpstrInitialDir = initialDir;
     }
-
+    
     ofn.lpstrTitle   = title;
     ofn.lpstrFilter  = filterBuffer;
     ofn.nFilterIndex = mSelectedType;
@@ -170,24 +174,38 @@ NS_IMETHODIMP nsFilePicker::Show(PRInt16 *retval)
 
     ofn.Flags = OFN_NOCHANGEDIR | OFN_SHAREAWARE | OFN_LONGNAMES | OFN_OVERWRITEPROMPT | OFN_HIDEREADONLY;
 
-    // Get file extension from suggested filename
-    //  to detect if we are saving an html file
-    //XXX: nsIFile SHOULD HAVE A GetExtension() METHOD!
-    PRInt32 extIndex = mDefault.RFind(".");
-    if ( extIndex >= 0) {
-      nsAutoString ext;
-      mDefault.Right(ext, mDefault.Length() - extIndex);
-      // Should we test for ".cgi", ".asp", ".jsp" and other
-      // "generated" html pages?
+    if (!mDefaultExtension.IsEmpty()) {
+      // Someone was cool and told us what to do
+      char *convertedExt = ConvertToFileSystemCharset(mDefaultExtension.get());
+      if (!convertedExt) {
+        mDefaultExtension.ToCString(extensionBuffer, MAX_EXTENSION_LENGTH);
+      }
+      else {
+        PL_strncpyz(extensionBuffer, convertedExt, MAX_EXTENSION_LENGTH+1);
+        nsMemory::Free( convertedExt );
+      }
+      ofn.lpstrDefExt = extensionBuffer;
+    }
+    else {
+      // Get file extension from suggested filename
+      //  to detect if we are saving an html file
+      //XXX: nsIFile SHOULD HAVE A GetExtension() METHOD!
+      PRInt32 extIndex = mDefault.RFind(".");
+      if ( extIndex >= 0) {
+        nsAutoString ext;
+        mDefault.Right(ext, mDefault.Length() - extIndex);
+        // Should we test for ".cgi", ".asp", ".jsp" and other
+        // "generated" html pages?
 
-      if ( ext.EqualsIgnoreCase(".htm")  ||
-           ext.EqualsIgnoreCase(".html") ||
-           ext.EqualsIgnoreCase(".shtml") ) {
-        // This is supposed to append ".htm" if user doesn't supply an extension
-        //XXX Actually, behavior is sort of weird:
-        //    often appends ".html" even if you have an extension
-        //    It obeys your extension if you put quotes around name
-        ofn.lpstrDefExt = htmExt;
+        if ( ext.EqualsIgnoreCase(".htm")  ||
+             ext.EqualsIgnoreCase(".html") ||
+             ext.EqualsIgnoreCase(".shtml") ) {
+          // This is supposed to append ".htm" if user doesn't supply an extension
+          //XXX Actually, behavior is sort of weird:
+          //    often appends ".html" even if you have an extension
+          //    It obeys your extension if you put quotes around name
+          ofn.lpstrDefExt = htmExt;
+        }
       }
     }
 
@@ -355,6 +373,25 @@ NS_IMETHODIMP nsFilePicker::GetDefaultString(PRUnichar **aString)
   return NS_ERROR_FAILURE;
 }
 
+//-------------------------------------------------------------------------
+//
+// The default extension to use for files
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsFilePicker::GetDefaultExtension(PRUnichar **aExtension)
+{
+  *aExtension = ToNewUnicode(mDefaultExtension);
+  if (!*aExtension)
+    return NS_ERROR_OUT_OF_MEMORY;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::SetDefaultExtension(const PRUnichar *aExtension)
+{
+  mDefaultExtension = aExtension;
+  return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Set the filter index
diff --git a/mozilla/widget/src/windows/nsFilePicker.h b/mozilla/widget/src/windows/nsFilePicker.h
index e895205f307..94fd3d8e8dc 100644
--- a/mozilla/widget/src/windows/nsFilePicker.h
+++ b/mozilla/widget/src/windows/nsFilePicker.h
@@ -47,6 +47,8 @@ public:
     // nsIFilePicker (less what's in nsBaseFilePicker)
   NS_IMETHOD GetDefaultString(PRUnichar * *aDefaultString);
   NS_IMETHOD SetDefaultString(const PRUnichar * aDefaultString);
+  NS_IMETHOD GetDefaultExtension(PRUnichar * *aDefaultExtension);
+  NS_IMETHOD SetDefaultExtension(const PRUnichar * aDefaultExtension);
   NS_IMETHOD GetDisplayDirectory(nsILocalFile * *aDisplayDirectory);
   NS_IMETHOD SetDisplayDirectory(nsILocalFile * aDisplayDirectory);
   NS_IMETHOD GetFilterIndex(PRInt32 *aFilterIndex);
@@ -73,6 +75,7 @@ protected:
   PRInt16                mMode;
   nsCString              mFile;
   nsString               mDefault;
+  nsString               mDefaultExtension;
   nsString               mFilterList;
   nsIUnicodeEncoder*     mUnicodeEncoder;
   nsIUnicodeDecoder*     mUnicodeDecoder;
diff --git a/mozilla/xpfe/communicator/resources/content/contentAreaUtils.js b/mozilla/xpfe/communicator/resources/content/contentAreaUtils.js
index a9388587451..1026e29cc87 100644
--- a/mozilla/xpfe/communicator/resources/content/contentAreaUtils.js
+++ b/mozilla/xpfe/communicator/resources/content/contentAreaUtils.js
@@ -232,7 +232,9 @@ function foundHeaderInfo(aSniffer, aData)
   var defaultFileName = getDefaultFileName(aData.fileName, 
                                            aSniffer.suggestedFileName, 
                                            aSniffer.uri);
-  fp.defaultString = getNormalizedLeafName(defaultFileName, contentType);
+  var defaultExtension = getDefaultExtension(defaultFileName, aSniffer.uri, contentType);
+  fp.defaultExtension = defaultExtension;
+  fp.defaultString = getNormalizedLeafName(defaultFileName, defaultExtension);
   
   if (fp.show() == Components.interfaces.nsIFilePicker.returnCancel || !fp.file)
     return;
@@ -243,7 +245,6 @@ function foundHeaderInfo(aSniffer, aData)
   prefs.setComplexValue("dir", nsILocalFile, directory);
     
   fp.file.leafName = validateFileName(fp.file.leafName);
-  fp.file.leafName = getNormalizedLeafName(fp.file.leafName, contentType);
   
   // If we're saving a document, and are saving either in complete mode or 
   // as converted text, pass the document to the web browser persist component.
@@ -510,36 +511,64 @@ function validateFileName(aFileName)
   return aFileName.replace(re, "_");
 }
 
-function getNormalizedLeafName(aFile, aContentType)
+function getNormalizedLeafName(aFile, aDefaultExtension)
 {
-  // Fix up the file name we're saving to so that if the user enters
-  // no extension, an appropriate one is appended. 
-  var leafName = aFile;
-
-  var mimeInfo = getMIMEInfoForType(aContentType);
-  if (mimeInfo) {
-    var extCount = { };
-    var extList = { };
-    mimeInfo.GetFileExtensions(extCount, extList);
-
-    const stdURLContractID = "@mozilla.org/network/standard-url;1";
-    const stdURLIID = Components.interfaces.nsIURI;
-    var uri = Components.classes[stdURLContractID].createInstance(stdURLIID);
-    var url = uri.QueryInterface(Components.interfaces.nsIURL); 
-    url.filePath = aFile;
-    
-    if (aContentType == "text/html") {
-      if ((url.fileExtension && 
-           url.fileExtension != "htm" && url.fileExtension != "html") ||
-          (!url.fileExtension))
-        return leafName + ".html";
-    }
-
-    if (!url.fileExtension)
-      return leafName + "." + extList.value[0];
+  if (!aDefaultExtension)
+    return aFile;
+  
+  // Fix up the file name we're saving to to include the default extension
+  const stdURLContractID = "@mozilla.org/network/standard-url;1";
+  const stdURLIID = Components.interfaces.nsIURL;
+  var url = Components.classes[stdURLContractID].createInstance(stdURLIID);
+  url.filePath = aFile;
+  
+  if (url.fileExtension != aDefaultExtension) {
+    return aFile + "." + aDefaultExtension;
+  }
+
+  return aFile;
+}
+
+function getDefaultExtension(aFilename, aURI, aContentType)
+{
+  // This mirrors some code in nsExternalHelperAppService::DoContent
+  // Use the filename first and then the URI if that fails
+  
+  var mimeInfo = getMIMEInfoForType(aContentType);
+
+  // First try the extension from the filename
+  const stdURLContractID = "@mozilla.org/network/standard-url;1";
+  const stdURLIID = Components.interfaces.nsIURL;
+  var url = Components.classes[stdURLContractID].createInstance(stdURLIID);
+  url.filePath = aFilename;
+
+  var ext = url.fileExtension;
+
+  if (ext && mimeInfo.ExtensionExists(ext)) {
+    return ext;
+  }
+  
+  // Well, that failed.  Now try the extension from the URI
+  var urlext;
+  try {
+    url = aURI.QueryInterface(Components.interfaces.nsIURL);
+    urlext = url.fileExtension;
+  } catch (e) {
+  }
+
+  if (urlext && mimeInfo.ExtensionExists(urlext)) {
+    return urlext;
+  }
+  else {
+    try {
+      return mimeInfo.primaryExtension;
+    }
+    catch (e) {
+      // Fall back on the extensions in the filename and URI for lack
+      // of anything better.
+      return ext || urlext;
+    }
   }
- 
-  return leafName;
 }
 
 function isDocumentType(aContentType)
diff --git a/mozilla/xpfe/components/filepicker/src/nsFilePicker.js b/mozilla/xpfe/components/filepicker/src/nsFilePicker.js
index 95212721ebd..871f9fdf968 100644
--- a/mozilla/xpfe/components/filepicker/src/nsFilePicker.js
+++ b/mozilla/xpfe/components/filepicker/src/nsFilePicker.js
@@ -100,6 +100,10 @@ nsFilePicker.prototype = {
   set defaultString(a) { this.mDefaultString = a; },
   get defaultString()  { return this.mDefaultString; },
 
+  /* attribute wstring defaultExtension */
+  set defaultExtension(ext) { },
+  get defaultExtension() { return ""; },
+  
   /* attribute long filterIndex; */
   set filterIndex(a) { this.mFilterIndex = a; },
   get filterIndex() { return this.mFilterIndex; },
diff --git a/mozilla/xpfe/components/filepicker/src/nsFilePicker.js.in b/mozilla/xpfe/components/filepicker/src/nsFilePicker.js.in
index 95212721ebd..871f9fdf968 100644
--- a/mozilla/xpfe/components/filepicker/src/nsFilePicker.js.in
+++ b/mozilla/xpfe/components/filepicker/src/nsFilePicker.js.in
@@ -100,6 +100,10 @@ nsFilePicker.prototype = {
   set defaultString(a) { this.mDefaultString = a; },
   get defaultString()  { return this.mDefaultString; },
 
+  /* attribute wstring defaultExtension */
+  set defaultExtension(ext) { },
+  get defaultExtension() { return ""; },
+  
   /* attribute long filterIndex; */
   set filterIndex(a) { this.mFilterIndex = a; },
   get filterIndex() { return this.mFilterIndex; },