--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -216,16 +216,22 @@ pref("browser.urlbar.filter.javascript",
 // the maximum number of results to show in autocomplete when doing richResults
 pref("browser.urlbar.maxRichResults", 25);
 // Size of "chunks" affects the number of places to process between each search
 // timeout (ms). Too big and the UI will be unresponsive; too small and we'll
 // be waiting on the timeout too often without many results.
 pref("browser.urlbar.search.chunkSize", 1000);
 pref("browser.urlbar.search.timeout", 50);
 
+// Number of milliseconds to wait for the http headers (and thus
+// the Content-Disposition filename) before giving up and falling back to 
+// picking a filename without that info in hand so that the user sees some
+// feedback from their action.
+pref("browser.download.saveLinkAsFilenameTimeout", 1000);
+
 pref("browser.download.useDownloadDir", true);
 pref("browser.download.folderList", 0);
 pref("browser.download.manager.showAlertOnComplete", true);
 pref("browser.download.manager.showAlertInterval", 2000);
 pref("browser.download.manager.retention", 2);
 pref("browser.download.manager.showWhenStarting", true);
 pref("browser.download.manager.useWindow", true);
 pref("browser.download.manager.closeWhenDone", false);

--- a/browser/base/content/nsContextMenu.js
+++ b/browser/base/content/nsContextMenu.js
@@ -36,16 +36,17 @@
 #   Tom Germeau <tom.germeau@epigoon.com>
 #   Jesse Ruderman <jruderman@gmail.com>
 #   Joe Hughes <joe@retrovirus.com>
 #   Pamela Greene <pamg.bugs@gmail.com>
 #   Michael Ventnor <ventnors_dogs234@yahoo.com.au>
 #   Simon Bünzli <zeniko@gmail.com>
 #   Gijs Kruitbosch <gijskruitbosch@gmail.com>
 #   Ehsan Akhgari <ehsan.akhgari@gmail.com>
+#   Dan Mosedale <dmose@mozilla.org>
 #
 # Alternatively, the contents of this file may be used under the terms of
 # either the GNU General Public License Version 2 or later (the "GPL"), or
 # the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 # in which case the provisions of the GPL or the LGPL are applicable instead
 # of those above. If you wish to allow use of your version of this file only
 # under the terms of either the GPL or the LGPL, and not to allow others to
 # use your version of this file under the terms of the MPL, indicate your
@@ -821,20 +822,132 @@ nsContextMenu.prototype = {
 
   // Save URL of clicked-on frame.
   saveFrame: function () {
     saveDocument(this.target.ownerDocument);
   },
 
   // Save URL of clicked-on link.
   saveLink: function() {
+    // canonical def in nsURILoader.h
+    const NS_ERROR_SAVE_LINK_AS_TIMEOUT = 0x805d0020;
+    
     var doc =  this.target.ownerDocument;
     urlSecurityCheck(this.linkURL, doc.nodePrincipal);
-    saveURL(this.linkURL, this.linkText(), null, true, false,
-            doc.documentURIObject);
+    var linkText = this.linkText();
+    var linkURL = this.linkURL;
+
+
+    // an object to proxy the data through to
+    // nsIExternalHelperAppService.doContent, which will wait for the
+    // appropriate MIME-type headers and then prompt the user with a
+    // file picker
+    function saveAsListener() {}
+    saveAsListener.prototype = {
+      extListener: null, 
+
+      onStartRequest: function saveLinkAs_onStartRequest(aRequest, aContext) {
+
+        // if the timer fired, the error status will have been caused by that,
+        // and we'll be restarting in onStopRequest, so no reason to notify
+        // the user
+        if (aRequest.status == NS_ERROR_SAVE_LINK_AS_TIMEOUT)
+          return;
+
+        timer.cancel();
+
+        // some other error occured; notify the user...
+        if (!Components.isSuccessCode(aRequest.status)) {
+          try {
+            const sbs = Cc["@mozilla.org/intl/stringbundle;1"].
+                        getService(Ci.nsIStringBundleService);
+            const bundle = sbs.createBundle(
+                    "chrome://mozapps/locale/downloads/downloads.properties");
+            
+            const title = bundle.GetStringFromName("downloadErrorAlertTitle");
+            const msg = bundle.GetStringFromName("downloadErrorGeneric");
+            
+            const promptSvc = Cc["@mozilla.org/embedcomp/prompt-service;1"].
+                              getService(Ci.nsIPromptService);
+            promptSvc.alert(doc.defaultView, title, msg);
+          } catch (ex) {}
+          return;
+        }
+
+        var extHelperAppSvc = 
+          Cc["@mozilla.org/uriloader/external-helper-app-service;1"].
+          getService(Ci.nsIExternalHelperAppService);
+        this.extListener = 
+          extHelperAppSvc.doContent(aRequest.contentType, aRequest, 
+                                    doc.defaultView, true);
+        this.extListener.onStartRequest(aRequest, aContext);
+      }, 
+
+      onStopRequest: function saveLinkAs_onStopRequest(aRequest, aContext, 
+                                                       aStatusCode) {
+        if (aStatusCode == NS_ERROR_SAVE_LINK_AS_TIMEOUT) {
+          // do it the old fashioned way, which will pick the best filename
+          // it can without waiting.
+          saveURL(linkURL, linkText, null, true, false, doc.documentURIObject);
+        }
+        if (this.extListener)
+          this.extListener.onStopRequest(aRequest, aContext, aStatusCode);
+      },
+       
+      onDataAvailable: function saveLinkAs_onDataAvailable(aRequest, aContext,
+                                                           aInputStream,
+                                                           aOffset, aCount) {
+        this.extListener.onDataAvailable(aRequest, aContext, aInputStream,
+                                         aOffset, aCount);
+      }
+    }
+
+    // in case we need to prompt the user for authentication
+    function callbacks() {}
+    callbacks.prototype = {
+      getInterface: function sLA_callbacks_getInterface(aIID) {
+        if (aIID.equals(Ci.nsIAuthPrompt) || aIID.equals(Ci.nsIAuthPrompt2)) {
+          var ww = Cc["@mozilla.org/embedcomp/window-watcher;1"].
+                   getService(Ci.nsIPromptFactory);
+          return ww.getPrompt(doc.defaultView, aIID);
+        }
+        throw Cr.NS_ERROR_NO_INTERFACE;
+      } 
+    }
+
+    // if it we don't have the headers after a short time, the user 
+    // won't have received any feedback from their click.  that's bad.  so
+    // we give up waiting for the filename. 
+    function timerCallback() {}
+    timerCallback.prototype = {
+      notify: function sLA_timer_notify(aTimer) {
+        channel.cancel(NS_ERROR_SAVE_LINK_AS_TIMEOUT);
+        return;
+      }
+    }
+
+    // set up a channel to do the saving
+    var ioService = Cc["@mozilla.org/network/io-service;1"].
+                    getService(Ci.nsIIOService);
+    var channel = ioService.newChannelFromURI(this.getLinkURI());
+    channel.notificationCallbacks = new callbacks();
+    channel.loadFlags |= Ci.nsIRequest.LOAD_BYPASS_CACHE |
+                         Ci.nsIChannel.LOAD_CALL_CONTENT_SNIFFERS;
+    if (channel instanceof Ci.nsIHttpChannel)
+      channel.referrer = doc.documentURIObject;
+
+    // fallback to the old way if we don't see the headers quickly 
+    var timeToWait = 
+      gPrefService.getIntPref("browser.download.saveLinkAsFilenameTimeout");
+    var timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+    timer.initWithCallback(new timerCallback(), timeToWait,
+                           timer.TYPE_ONE_SHOT);
+
+    // kick off the channel with our proxy object as the listener
+    channel.asyncOpen(new saveAsListener(), null);
   },
 
   sendLink: function() {
     // we don't know the title of the link so pass in an empty string
     MailIntegration.sendMessage( this.linkURL, "" );
   },
 
   // Save URL of clicked-on image.

--- a/uriloader/base/nsURILoader.cpp
+++ b/uriloader/base/nsURILoader.cpp
@@ -589,16 +589,17 @@ nsresult nsDocumentOpenInfo::DispatchCon
     if (isGuessFromExt) {
       mContentType = APPLICATION_GUESS_FROM_EXT;
       aChannel->SetContentType(NS_LITERAL_CSTRING(APPLICATION_GUESS_FROM_EXT));
     }
 
     rv = helperAppService->DoContent(mContentType,
                                      request,
                                      m_originalContext,
+                                     PR_FALSE,
                                      getter_AddRefs(m_targetStreamListener));
     if (NS_FAILED(rv)) {
       request->SetLoadFlags(loadFlags);
       m_targetStreamListener = nsnull;
     }
   }
       
   NS_ASSERTION(m_targetStreamListener || NS_FAILED(rv),

--- a/uriloader/base/nsURILoader.h
+++ b/uriloader/base/nsURILoader.h
@@ -94,9 +94,15 @@ protected:
 
 /**
  * The load has been cancelled because it was found on a malware or phishing blacklist.
  * XXX: this belongs in an nsDocShellErrors.h file of some sort.
  */
 #define NS_ERROR_MALWARE_URI   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_URILOADER, 30)
 #define NS_ERROR_PHISHING_URI  NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_URILOADER, 31)
 
+/**
+ * Used when "Save Link As..." doesn't see the headers quickly enough to choose
+ * a filename.  See nsContextMenu.js. 
+ */
+#define NS_ERROR_SAVE_LINK_AS_TIMEOUT  NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_URILOADER, 32);
+
 #endif /* nsURILoader_h__ */

--- a/uriloader/exthandler/nsExternalHelperAppService.cpp
+++ b/uriloader/exthandler/nsExternalHelperAppService.cpp
@@ -519,16 +519,17 @@ nsresult nsExternalHelperAppService::Ini
 nsExternalHelperAppService::~nsExternalHelperAppService()
 {
   gExtProtSvc = nsnull;
 }
 
 NS_IMETHODIMP nsExternalHelperAppService::DoContent(const nsACString& aMimeContentType,
                                                     nsIRequest *aRequest,
                                                     nsIInterfaceRequestor *aWindowContext,
+                                                    PRBool aForceSave,
                                                     nsIStreamListener ** aStreamListener)
 {
   nsAutoString fileName;
   nsCAutoString fileExtension;
   PRUint32 reason = nsIHelperAppLauncherDialog::REASON_CANTHANDLE;
   nsresult rv;
 
   // Get the file extension and name that we will need later
@@ -635,17 +636,18 @@ NS_IMETHODIMP nsExternalHelperAppService
   // nsExternalAppHandler
   nsCAutoString buf;
   mimeInfo->GetPrimaryExtension(buf);
 
   nsExternalAppHandler * handler = new nsExternalAppHandler(mimeInfo,
                                                             buf,
                                                             aWindowContext,
                                                             fileName,
-                                                            reason);
+                                                            reason,
+                                                            aForceSave);
   if (!handler)
     return NS_ERROR_OUT_OF_MEMORY;
   NS_ADDREF(*aStreamListener = handler);
   
   return NS_OK;
 }
 
 NS_IMETHODIMP nsExternalHelperAppService::ApplyDecodingForExtension(const nsACString& aExtension,
@@ -986,21 +988,22 @@ NS_INTERFACE_MAP_BEGIN(nsExternalAppHand
    NS_INTERFACE_MAP_ENTRY(nsICancelable)
    NS_INTERFACE_MAP_ENTRY(nsITimerCallback)
 NS_INTERFACE_MAP_END_THREADSAFE
 
 nsExternalAppHandler::nsExternalAppHandler(nsIMIMEInfo * aMIMEInfo,
                                            const nsCSubstring& aTempFileExtension,
                                            nsIInterfaceRequestor* aWindowContext,
                                            const nsAString& aSuggestedFilename,
-                                           PRUint32 aReason)
+                                           PRUint32 aReason, PRBool aForceSave)
 : mMimeInfo(aMIMEInfo)
 , mWindowContext(aWindowContext)
 , mWindowToClose(nsnull)
 , mSuggestedFileName(aSuggestedFilename)
+, mForceSave(aForceSave)
 , mCanceled(PR_FALSE)
 , mShouldCloseWindow(PR_FALSE)
 , mReceivedDispositionInfo(PR_FALSE)
 , mStopRequestIssued(PR_FALSE)
 , mProgressListenerInitialized(PR_FALSE)
 , mReason(aReason)
 , mContentLength(-1)
 , mProgress(0)
@@ -1465,16 +1468,23 @@ NS_IMETHODIMP nsExternalAppHandler::OnSt
 
   // OK, now check why we're here
   if (!alwaysAsk && mReason != nsIHelperAppLauncherDialog::REASON_CANTHANDLE) {
     // Force asking if we're not saving.  See comment back when we fetched the
     // alwaysAsk boolean for details.
     alwaysAsk = (action != nsIMIMEInfo::saveToDisk);
   }
 
+  // if we were told that we _must_ save to disk without asking, all the stuff
+  // before this is irrelevant; override it
+  if (mForceSave) {
+    alwaysAsk = PR_FALSE;
+    action = nsIMIMEInfo::saveToDisk;
+  }
+  
   if (alwaysAsk)
   {
     // do this first! make sure we don't try to take an action until the user tells us what they want to do
     // with it...
     mReceivedDispositionInfo = PR_FALSE; 
 
     // invoke the dialog!!!!! use mWindowContext as the window context parameter for the dialog request
     mDialog = do_CreateInstance( NS_IHELPERAPPLAUNCHERDLG_CONTRACTID, &rv );

--- a/uriloader/exthandler/nsExternalHelperAppService.h
+++ b/uriloader/exthandler/nsExternalHelperAppService.h
@@ -246,17 +246,17 @@ public:
    * @param aWindowContext Window context, as passed to DoContent
    * @param aFileName      The filename to use
    * @param aReason        A constant from nsIHelperAppLauncherDialog indicating
    *                       why the request is handled by a helper app.
    */
   nsExternalAppHandler(nsIMIMEInfo * aMIMEInfo, const nsCSubstring& aFileExtension,
                        nsIInterfaceRequestor * aWindowContext,
                        const nsAString& aFilename,
-                       PRUint32 aReason);
+                       PRUint32 aReason, PRBool aForceSave);
 
   ~nsExternalAppHandler();
 
 protected:
   nsCOMPtr<nsIFile> mTempFile;
   nsCOMPtr<nsIURI> mSourceUrl;
   nsString mTempFileExtension;
   /**
@@ -276,16 +276,23 @@ protected:
   /**
    * The following field is set if we were processing an http channel that had
    * a content disposition header which specified the SUGGESTED file name we
    * should present to the user in the save to disk dialog. 
    */
   nsString mSuggestedFileName;
 
   /**
+   * If set, this handler should forcibly save the file to disk regardless of
+   * MIME info settings or anything else, without ever popping up the 
+   * unknown content type handling dialog.
+   */
+  PRPackedBool mForceSave;
+  
+  /**
    * The canceled flag is set if the user canceled the launching of this
    * application before we finished saving the data to a temp file.
    */
   PRPackedBool mCanceled;
 
   /**
    * This is set based on whether the channel indicates that a new window
    * was opened specifically for this download.  If so, then we

--- a/uriloader/exthandler/nsIExternalHelperAppService.idl
+++ b/uriloader/exthandler/nsIExternalHelperAppService.idl
@@ -46,33 +46,36 @@ interface nsIFile;
 interface nsIMIMEInfo;
 interface nsIWebProgressListener2;
 interface nsIInterfaceRequestor;
 
 /**
  * The external helper app service is used for finding and launching
  * platform specific external applications for a given mime content type.
  */
-[scriptable, uuid(0ea90cf3-2dd9-470f-8f76-f141743c5678)]
+[scriptable, uuid(9e456297-ba3e-42b1-92bd-b7db014268cb)]
 interface nsIExternalHelperAppService : nsISupports
 {
   /**
    * Binds an external helper application to a stream listener. The caller
    * should pump data into the returned stream listener. When the OnStopRequest
    * is issued, the stream listener implementation will launch the helper app
    * with this data.
    * @param aMimeContentType The content type of the incoming data
    * @param aRequest The request corresponding to the incoming data
    * @param aWindowContext Use GetInterface to retrieve properties like the
    *                       dom window or parent window...
    *                       The service might need this in order to bring up dialogs.
+   * @param aForceSave True to always save this content to disk, regardless of
+   *                   nsIMIMEInfo and other such influences.
    * @return A nsIStreamListener which the caller should pump the data into.
    */
   nsIStreamListener doContent (in ACString aMimeContentType, in nsIRequest aRequest,
-                               in nsIInterfaceRequestor aWindowContext); 
+                               in nsIInterfaceRequestor aWindowContext,
+                               in boolean aForceSave); 
 
   /**
    * Returns true if data from a URL with this extension combination
    * is to be decoded from aEncodingType prior to saving or passing
    * off to helper apps, false otherwise.
    */
   boolean applyDecodingForExtension(in AUTF8String aExtension,
                                     in ACString aEncodingType);