diff --git a/mozilla/content/base/src/nsDocumentViewer.cpp b/mozilla/content/base/src/nsDocumentViewer.cpp
index 37d82603967..088a22c32b2 100644
--- a/mozilla/content/base/src/nsDocumentViewer.cpp
+++ b/mozilla/content/base/src/nsDocumentViewer.cpp
@@ -120,7 +120,7 @@
 #include "nsIFocusController.h"
 
 #include "nsIScrollableView.h"
-#include "nsIHTMLDocument.h"
+#include "nsIScrollable.h"
 #include "nsITimelineService.h"
 #include "nsGfxCIID.h"
 
@@ -678,11 +678,23 @@ DocumentViewerImpl::InitPresentationStuff(PRBool aDoInitialReflow)
   mViewManager->SetDefaultBackgroundColor(mPresContext->DefaultBackgroundColor());
 
   if (aDoInitialReflow) {
-    nsCOMPtr<nsIHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
-    if (htmlDoc) {
-      nsCOMPtr<nsIDOMHTMLFrameSetElement> frameset =
-        do_QueryInterface(mDocument->GetRootContent());
-      htmlDoc->SetIsFrameset(frameset != nsnull);
+    nsCOMPtr<nsIScrollable> sc = do_QueryInterface(mContainer);
+
+    if (sc) {
+      nsCOMPtr<nsIDOMHTMLFrameSetElement> frameset(do_QueryInterface(mDocument->GetRootContent()));
+
+      if (frameset) {
+        // If this is a frameset (i.e. not a frame) then we never want
+        // scrollbars on it, the scrollbars go inside the frames
+        // inside the frameset...
+
+        sc->SetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_Y,
+                                           nsIScrollable::Scrollbar_Never);
+        sc->SetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_X,
+                                           nsIScrollable::Scrollbar_Never);
+      } else {
+        sc->ResetScrollbarPreferences();
+      }
     }
 
     // Initial reflow
diff --git a/mozilla/content/html/document/src/nsHTMLContentSink.cpp b/mozilla/content/html/document/src/nsHTMLContentSink.cpp
index f2f2fefb770..650b90da514 100644
--- a/mozilla/content/html/document/src/nsHTMLContentSink.cpp
+++ b/mozilla/content/html/document/src/nsHTMLContentSink.cpp
@@ -108,6 +108,7 @@
 #include "nsTimer.h"
 #include "nsITimer.h"
 #include "nsDOMError.h"
+#include "nsIScrollable.h"
 #include "nsContentPolicyUtils.h"
 #include "nsIScriptContext.h"
 #include "nsStyleLinkElement.h"
@@ -3645,9 +3646,24 @@ HTMLContentSink::StartLayout()
 
   mLastNotificationTime = PR_Now();
 
-  mHTMLDocument->SetIsFrameset(mFrameset != nsnull);
+  // If it's a frameset document then disable scrolling.
+  // Else, reset scrolling to default settings for this shell.
+  // This must happen before the initial reflow, when we create the root frame
+  nsCOMPtr<nsIScrollable> scrollableContainer = do_QueryInterface(mDocShell);
+  if (scrollableContainer) {
+    if (mFrameset) {
+      scrollableContainer->
+        SetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_Y,
+                                       nsIScrollable::Scrollbar_Never);
+      scrollableContainer->
+        SetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_X,
+                                       nsIScrollable::Scrollbar_Never);
+    } else {
+      scrollableContainer->ResetScrollbarPreferences();
+    }
+  }
 
-  nsContentSink::StartLayout(mFrameset != nsnull);
+  nsContentSink::StartLayout(!!mFrameset);
 }
 
 void
diff --git a/mozilla/content/html/document/src/nsHTMLDocument.h b/mozilla/content/html/document/src/nsHTMLDocument.h
index 3b0037b6e86..3ff0e760270 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.h
+++ b/mozilla/content/html/document/src/nsHTMLDocument.h
@@ -119,9 +119,6 @@ public:
     return mWriteLevel != PRUint32(0);
   }
 
-  virtual PRBool GetIsFrameset() { return mIsFrameset; }
-  virtual void SetIsFrameset(PRBool aFrameset) { mIsFrameset = aFrameset; }
-
   virtual void ContentAppended(nsIContent* aContainer,
                                PRInt32 aNewIndexInContainer);
   virtual void ContentInserted(nsIContent* aContainer,
@@ -322,8 +319,6 @@ protected:
    */
   PRPackedBool mDomainWasSet;
 
-  PRPackedBool mIsFrameset;
-
   PLDHashTable mIdAndNameHashTable;
 
   nsCOMPtr<nsIWyciwygChannel> mWyciwygChannel;
diff --git a/mozilla/content/html/document/src/nsIHTMLDocument.h b/mozilla/content/html/document/src/nsIHTMLDocument.h
index 12eae9914b5..ab9848cfbc8 100644
--- a/mozilla/content/html/document/src/nsIHTMLDocument.h
+++ b/mozilla/content/html/document/src/nsIHTMLDocument.h
@@ -111,9 +111,6 @@ public:
   virtual PRInt32 GetNumFormsSynchronous() = 0;
   
   virtual PRBool IsWriting() = 0;
-
-  virtual PRBool GetIsFrameset() = 0;
-  virtual void SetIsFrameset(PRBool aFrameset) = 0;
 };
 
 #endif /* nsIHTMLDocument_h___ */
diff --git a/mozilla/content/html/document/src/nsMediaDocument.cpp b/mozilla/content/html/document/src/nsMediaDocument.cpp
index 2fe13f86d56..c23378527df 100644
--- a/mozilla/content/html/document/src/nsMediaDocument.cpp
+++ b/mozilla/content/html/document/src/nsMediaDocument.cpp
@@ -267,6 +267,13 @@ nsMediaDocument::CreateSyntheticDocument()
 nsresult
 nsMediaDocument::StartLayout()
 {
+  // Reset scrolling to default settings for this shell.
+  // This must happen before the initial reflow, when we create the root frame
+  nsCOMPtr<nsIScrollable> scrollableContainer(do_QueryReferent(mDocumentContainer));
+  if (scrollableContainer) {
+    scrollableContainer->ResetScrollbarPreferences();
+  }
+
   PRUint32 numberOfShells = GetNumberOfShells();
   for (PRUint32 i = 0; i < numberOfShells; i++) {
     nsIPresShell *shell = GetShellAt(i);
diff --git a/mozilla/content/xml/document/src/nsXMLContentSink.cpp b/mozilla/content/xml/document/src/nsXMLContentSink.cpp
index 5a87993f2ba..4c8ba67f5aa 100644
--- a/mozilla/content/xml/document/src/nsXMLContentSink.cpp
+++ b/mozilla/content/xml/document/src/nsXMLContentSink.cpp
@@ -78,6 +78,7 @@
 #include "prlog.h"
 #include "prmem.h"
 #include "nsParserUtils.h"
+#include "nsIScrollable.h"
 #include "nsRect.h"
 #include "nsGenericElement.h"
 #include "nsIWebNavigation.h"
@@ -831,6 +832,12 @@ nsXMLContentSink::PopContent()
 void
 nsXMLContentSink::StartLayout()
 {
+  // Reset scrolling to default settings for this shell.
+  // This must happen before the initial reflow, when we create the root frame
+  nsCOMPtr<nsIScrollable> scrollableContainer(do_QueryInterface(mDocShell));
+  if (scrollableContainer) {
+    scrollableContainer->ResetScrollbarPreferences();
+  }
   PRBool topLevelFrameset = PR_FALSE;
   nsCOMPtr<nsIDocShellTreeItem> docShellAsItem(do_QueryInterface(mDocShell));
   if (docShellAsItem) {
diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index 486c4fe72b6..e412428bd2a 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -268,6 +268,7 @@ nsDocShell::nsDocShell():
     mMarginHeight(0),
     mItemType(typeContent),
     mContentListener(nsnull),
+    mCurrentScrollbarPref(Scrollbar_Auto, Scrollbar_Auto),
     mDefaultScrollbarPref(Scrollbar_Auto, Scrollbar_Auto),
     mEditorData(nsnull),
     mParent(nsnull),
@@ -3652,6 +3653,29 @@ nsDocShell::SetScrollRangeEx(PRInt32 minHorizontalPos,
     return NS_ERROR_FAILURE;
 }
 
+// Get scroll setting for this document only
+//
+// One important client is nsCSSFrameConstructor::ConstructRootFrame()
+NS_IMETHODIMP
+nsDocShell::GetCurrentScrollbarPreferences(PRInt32 scrollOrientation,
+                                           PRInt32 * scrollbarPref)
+{
+    NS_ENSURE_ARG_POINTER(scrollbarPref);
+    switch (scrollOrientation) {
+    case ScrollOrientation_X:
+        *scrollbarPref = mCurrentScrollbarPref.x;
+        return NS_OK;
+
+    case ScrollOrientation_Y:
+        *scrollbarPref = mCurrentScrollbarPref.y;
+        return NS_OK;
+
+    default:
+        NS_ENSURE_TRUE(PR_FALSE, NS_ERROR_INVALID_ARG);
+    }
+    return NS_ERROR_FAILURE;
+}
+
 // This returns setting for all documents in this webshell
 NS_IMETHODIMP
 nsDocShell::GetDefaultScrollbarPreferences(PRInt32 scrollOrientation,
@@ -3673,14 +3697,39 @@ nsDocShell::GetDefaultScrollbarPreferences(PRInt32 scrollOrientation,
     return NS_ERROR_FAILURE;
 }
 
-// Set scrolling preference for all documents in this shell
+// Set scrolling preference for this document only.
 //
 // There are three possible values stored in the shell:
-//  1) nsIScrollable::Scrollbar_Never = no scrollbar
-//  2) nsIScrollable::Scrollbar_Auto = scrollbar appears if the document
-//     being displayed would normally have scrollbar
-//  3) nsIScrollable::Scrollbar_Always = scrollbar always appears
+//  1) NS_STYLE_OVERFLOW_HIDDEN = no scrollbars
+//  2) NS_STYLE_OVERFLOW_AUTO = scrollbars appear if needed
+//  3) NS_STYLE_OVERFLOW_SCROLL = scrollbars always
 //
+// XXX Currently OVERFLOW_SCROLL isn't honored,
+//     as it is not implemented by Gfx scrollbars
+// XXX setting has no effect after the root frame is created
+//     as it is not implemented by Gfx scrollbars
+//
+// One important client is HTMLContentSink::StartLayout()
+NS_IMETHODIMP
+nsDocShell::SetCurrentScrollbarPreferences(PRInt32 scrollOrientation,
+                                           PRInt32 scrollbarPref)
+{
+    switch (scrollOrientation) {
+    case ScrollOrientation_X:
+        mCurrentScrollbarPref.x = scrollbarPref;
+        return NS_OK;
+
+    case ScrollOrientation_Y:
+        mCurrentScrollbarPref.y = scrollbarPref;
+        return NS_OK;
+
+    default:
+        NS_ENSURE_TRUE(PR_FALSE, NS_ERROR_INVALID_ARG);
+    }
+    return NS_ERROR_FAILURE;
+}
+
+// Set scrolling preference for all documents in this shell
 // One important client is nsHTMLFrameInnerFrame::CreateWebShell()
 NS_IMETHODIMP
 nsDocShell::SetDefaultScrollbarPreferences(PRInt32 scrollOrientation,
@@ -3701,6 +3750,19 @@ nsDocShell::SetDefaultScrollbarPreferences(PRInt32 scrollOrientation,
     return NS_ERROR_FAILURE;
 }
 
+// Reset 'current' scrollbar settings to 'default'.
+// This must be called before every document load or else
+// frameset scrollbar settings (e.g. <IFRAME SCROLLING="no">
+// will not be preserved.
+//
+// One important client is HTMLContentSink::StartLayout()
+NS_IMETHODIMP
+nsDocShell::ResetScrollbarPreferences()
+{
+    mCurrentScrollbarPref = mDefaultScrollbarPref;
+    return NS_OK;
+}
+
 NS_IMETHODIMP
 nsDocShell::GetScrollbarVisibility(PRBool * verticalVisible,
                                    PRBool * horizontalVisible)
diff --git a/mozilla/docshell/base/nsDocShell.h b/mozilla/docshell/base/nsDocShell.h
index 103bce59a1d..0806e5541c5 100644
--- a/mozilla/docshell/base/nsDocShell.h
+++ b/mozilla/docshell/base/nsDocShell.h
@@ -411,6 +411,7 @@ protected:
     nsCOMPtr<nsIGlobalHistory2> mGlobalHistory;
     nsCOMPtr<nsISupports>      mLoadCookie; // the load cookie associated with the window context.
     nsCOMPtr<nsIWebBrowserFind> mFind;
+    nsPoint                    mCurrentScrollbarPref; // this document only
     nsPoint                    mDefaultScrollbarPref; // persistent across doc loads
     // Reference to the SHEntry for this docshell until the page is destroyed.
     // Somebody give me better name
diff --git a/mozilla/docshell/base/nsIScrollable.idl b/mozilla/docshell/base/nsIScrollable.idl
index 909fc5a39e7..fb9616e1d5d 100644
--- a/mozilla/docshell/base/nsIScrollable.idl
+++ b/mozilla/docshell/base/nsIScrollable.idl
@@ -48,7 +48,7 @@
  * min and the max. 
  */
 
-[scriptable, uuid(919e792a-6490-40b8-bba5-f9e9ad5640c8)]
+[scriptable, uuid(70bd2967-288b-4d0b-880a-de0b7c15a77c)]
 interface nsIScrollable : nsISupports
 {
 	/*
@@ -114,8 +114,11 @@ interface nsIScrollable : nsISupports
 	default is 'scrolling preference for all documents in this shell'
 	resetScrollbarPreferences resets current to default
 	*/
+	long getCurrentScrollbarPreferences(in long scrollOrientation);
+	void setCurrentScrollbarPreferences(in long scrollOrientation, in long scrollbarPref);
 	long getDefaultScrollbarPreferences(in long scrollOrientation);
 	void setDefaultScrollbarPreferences(in long scrollOrientation, in long scrollbarPref);
+	void resetScrollbarPreferences();
 
 	/*
 	Get information about whether the vertical and horizontal scrollbars are
diff --git a/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp b/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp
index eec086f10e9..18474270d13 100644
--- a/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp
+++ b/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp
@@ -1524,6 +1524,15 @@ NS_IMETHODIMP nsWebBrowser::SetScrollRangeEx(PRInt32 aMinHorizontalPos,
       aMaxHorizontalPos, aMinVerticalPos, aMaxVerticalPos);
 }
 
+NS_IMETHODIMP nsWebBrowser::GetCurrentScrollbarPreferences(PRInt32 aScrollOrientation,
+   PRInt32* aScrollbarPref)
+{
+   NS_ENSURE_STATE(mDocShell);
+
+   return mDocShellAsScrollable->GetCurrentScrollbarPreferences(aScrollOrientation,
+      aScrollbarPref);
+}
+
 NS_IMETHODIMP nsWebBrowser::GetDefaultScrollbarPreferences(PRInt32 aScrollOrientation,
    PRInt32* aScrollbarPref)
 {
@@ -1533,6 +1542,16 @@ NS_IMETHODIMP nsWebBrowser::GetDefaultScrollbarPreferences(PRInt32 aScrollOrient
       aScrollbarPref);
 }
 
+NS_IMETHODIMP nsWebBrowser::SetCurrentScrollbarPreferences(PRInt32 aScrollOrientation,
+   PRInt32 aScrollbarPref)
+{
+   NS_ENSURE_STATE(mDocShell);
+
+   return mDocShellAsScrollable->SetCurrentScrollbarPreferences(aScrollOrientation,
+      aScrollbarPref);
+
+}
+
 NS_IMETHODIMP nsWebBrowser::SetDefaultScrollbarPreferences(PRInt32 aScrollOrientation,
    PRInt32 aScrollbarPref)
 {
@@ -1542,6 +1561,13 @@ NS_IMETHODIMP nsWebBrowser::SetDefaultScrollbarPreferences(PRInt32 aScrollOrient
       aScrollbarPref);
 }
 
+NS_IMETHODIMP nsWebBrowser::ResetScrollbarPreferences()
+{
+   NS_ENSURE_STATE(mDocShell);
+
+   return mDocShellAsScrollable->ResetScrollbarPreferences();
+}
+
 NS_IMETHODIMP nsWebBrowser::GetScrollbarVisibility(PRBool* aVerticalVisible,
    PRBool* aHorizontalVisible)
 {
diff --git a/mozilla/layout/base/nsCSSFrameConstructor.cpp b/mozilla/layout/base/nsCSSFrameConstructor.cpp
index a5c0948f6d3..1d484213ebb 100644
--- a/mozilla/layout/base/nsCSSFrameConstructor.cpp
+++ b/mozilla/layout/base/nsCSSFrameConstructor.cpp
@@ -3824,6 +3824,7 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIPresShell*        aPresShell,
   // for print-preview, but not when printing), then create a scroll frame that
   // will act as the scrolling mechanism for the viewport. 
   // XXX Do we even need a viewport when printing to a printer?
+  PRBool isScrollable = PR_TRUE;
 
   //isScrollable = PR_FALSE;
 
@@ -3836,6 +3837,8 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIPresShell*        aPresShell,
   //  2) NS_STYLE_OVERFLOW_AUTO = scrollbars appear if needed
   //  3) NS_STYLE_OVERFLOW_SCROLL = scrollbars always
   // Only need to create a scroll frame/view for cases 2 and 3.
+  // Currently OVERFLOW_SCROLL isn't honored, as
+  // scrollportview::SetScrollPref is not implemented.
 
   PRBool isHTML = aDocElement->IsContentOfType(nsIContent::eHTML);
   PRBool isXUL = PR_FALSE;
@@ -3845,13 +3848,28 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIPresShell*        aPresShell,
   }
 
   // Never create scrollbars for XUL documents
-  PRBool isScrollable = !isXUL;
-
-  // Never create scrollbars for frameset documents.
-  if (isHTML) {
-    nsCOMPtr<nsIHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
-    if (htmlDoc && htmlDoc->GetIsFrameset())
-      isScrollable = PR_FALSE;
+#ifdef MOZ_XUL
+  if (isXUL) {
+    isScrollable = PR_FALSE;
+  } else 
+#endif
+  {
+    nsresult rv;
+    if (aPresContext) {
+      nsCOMPtr<nsISupports> container = aPresContext->GetContainer();
+      if (container) {
+        nsCOMPtr<nsIScrollable> scrollableContainer = do_QueryInterface(container, &rv);
+        if (NS_SUCCEEDED(rv) && scrollableContainer) {
+          PRInt32 scrolling = -1;
+          // XXX We should get prefs for X and Y and deal with these independently!
+          scrollableContainer->GetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_Y,&scrolling);
+          if (nsIScrollable::Scrollbar_Never == scrolling) {
+            isScrollable = PR_FALSE;
+          }
+          // XXX NS_STYLE_OVERFLOW_SCROLL should create 'always on' scrollbars
+        }
+      }
+    }
   }
 
   if (isPaginated) {
diff --git a/mozilla/layout/base/nsDocumentViewer.cpp b/mozilla/layout/base/nsDocumentViewer.cpp
index 37d82603967..088a22c32b2 100644
--- a/mozilla/layout/base/nsDocumentViewer.cpp
+++ b/mozilla/layout/base/nsDocumentViewer.cpp
@@ -120,7 +120,7 @@
 #include "nsIFocusController.h"
 
 #include "nsIScrollableView.h"
-#include "nsIHTMLDocument.h"
+#include "nsIScrollable.h"
 #include "nsITimelineService.h"
 #include "nsGfxCIID.h"
 
@@ -678,11 +678,23 @@ DocumentViewerImpl::InitPresentationStuff(PRBool aDoInitialReflow)
   mViewManager->SetDefaultBackgroundColor(mPresContext->DefaultBackgroundColor());
 
   if (aDoInitialReflow) {
-    nsCOMPtr<nsIHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
-    if (htmlDoc) {
-      nsCOMPtr<nsIDOMHTMLFrameSetElement> frameset =
-        do_QueryInterface(mDocument->GetRootContent());
-      htmlDoc->SetIsFrameset(frameset != nsnull);
+    nsCOMPtr<nsIScrollable> sc = do_QueryInterface(mContainer);
+
+    if (sc) {
+      nsCOMPtr<nsIDOMHTMLFrameSetElement> frameset(do_QueryInterface(mDocument->GetRootContent()));
+
+      if (frameset) {
+        // If this is a frameset (i.e. not a frame) then we never want
+        // scrollbars on it, the scrollbars go inside the frames
+        // inside the frameset...
+
+        sc->SetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_Y,
+                                           nsIScrollable::Scrollbar_Never);
+        sc->SetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_X,
+                                           nsIScrollable::Scrollbar_Never);
+      } else {
+        sc->ResetScrollbarPreferences();
+      }
     }
 
     // Initial reflow
diff --git a/mozilla/layout/base/public/nsIScrollableFrame.h b/mozilla/layout/base/public/nsIScrollableFrame.h
index feb798e9210..6907cae2854 100644
--- a/mozilla/layout/base/public/nsIScrollableFrame.h
+++ b/mozilla/layout/base/public/nsIScrollableFrame.h
@@ -67,10 +67,10 @@ public:
 
   struct ScrollbarStyles {
     // one of NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN,
-    // NS_STYLE_OVERFLOW_AUTO
-    PRUint8 mHorizontal, mVertical;
-    ScrollbarStyles(PRUint8 h, PRUint8 v) : mHorizontal(h), mVertical(v) {}
-    ScrollbarStyles() {}
+    // NS_STYLE_OVERFLOW_VISIBLE, NS_STYLE_OVERFLOW_AUTO
+    PRInt32 mHorizontal;
+    PRInt32 mVertical;
+    ScrollbarStyles(PRInt32 h, PRInt32 v) : mHorizontal(h), mVertical(v) {}
   };
 
   virtual ScrollbarStyles GetScrollbarStyles() const = 0;
diff --git a/mozilla/layout/generic/nsGfxScrollFrame.cpp b/mozilla/layout/generic/nsGfxScrollFrame.cpp
index 00c7d8dc942..4608c28c76c 100644
--- a/mozilla/layout/generic/nsGfxScrollFrame.cpp
+++ b/mozilla/layout/generic/nsGfxScrollFrame.cpp
@@ -45,7 +45,6 @@
 #include "nsIServiceManager.h"
 #include "nsIView.h"
 #include "nsIScrollableView.h"
-#include "nsIScrollable.h"
 #include "nsIViewManager.h"
 #include "nsHTMLContainerFrame.h"
 #include "nsWidgetsCID.h"
@@ -1182,72 +1181,40 @@ NS_IMETHODIMP_(nsrefcnt) nsGfxScrollFrameInner::Release(void)
 
 NS_IMPL_QUERY_INTERFACE1(nsGfxScrollFrameInner, nsIScrollPositionListener)
 
-static void HandleScrollPref(nsIScrollable *aScrollable, PRInt32 aOrientation,
-                             PRUint8& aValue)
-{
-  PRInt32 pref;
-  aScrollable->GetDefaultScrollbarPreferences(aOrientation, &pref);
-  switch (pref) {
-    case nsIScrollable::Scrollbar_Auto:
-      // leave |aValue| untouched
-      break;
-    case nsIScrollable::Scrollbar_Never:
-      aValue = NS_STYLE_OVERFLOW_HIDDEN;
-      break;
-    case nsIScrollable::Scrollbar_Always:
-      aValue = NS_STYLE_OVERFLOW_SCROLL;
-      break;
-  }
-}
-
-static nsGfxScrollFrameInner::ScrollbarStyles
-ConvertOverflow(PRUint8 aOverflow)
-{
-  nsGfxScrollFrameInner::ScrollbarStyles result;
-  switch (aOverflow) {
-    case NS_STYLE_OVERFLOW_SCROLLBARS_VERTICAL:
-      result.mHorizontal = NS_STYLE_OVERFLOW_HIDDEN;
-      result.mVertical = NS_STYLE_OVERFLOW_SCROLL;
-      break;
-    case NS_STYLE_OVERFLOW_SCROLLBARS_HORIZONTAL:
-      result.mHorizontal = NS_STYLE_OVERFLOW_SCROLL;
-      result.mVertical = NS_STYLE_OVERFLOW_HIDDEN;
-      break;
-    default:
-      result.mHorizontal = aOverflow;
-      result.mVertical = aOverflow;
-  }
-  return result;
-}
-
 nsGfxScrollFrameInner::ScrollbarStyles
 nsGfxScrollFrameInner::GetScrollbarStylesFromFrame() const
 {
-  ScrollbarStyles result;
+  PRUint8 overflow;
   nsIFrame* parent = mOuter->GetParent();
   if (parent && parent->GetType() == nsLayoutAtoms::viewportFrame &&
       // Make sure we're actually the root scrollframe
       parent->GetFirstChild(nsnull) ==
         NS_STATIC_CAST(const nsIFrame*, mOuter)) {
-    nsPresContext *presContext = mOuter->GetPresContext();
-    result = ConvertOverflow(presContext->GetViewportOverflowOverride());
-
-    nsCOMPtr<nsISupports> container = presContext->GetContainer();
-    nsCOMPtr<nsIScrollable> scrollable = do_QueryInterface(container);
-    HandleScrollPref(scrollable, nsIScrollable::ScrollOrientation_X,
-                     result.mHorizontal);
-    HandleScrollPref(scrollable, nsIScrollable::ScrollOrientation_Y,
-                     result.mVertical);
+    overflow = mOuter->GetPresContext()->GetViewportOverflowOverride();
   } else {
-    result = ConvertOverflow(mOuter->GetStyleDisplay()->mOverflow);
+    overflow = mOuter->GetStyleDisplay()->mOverflow;
   }
 
-  NS_ASSERTION(result.mHorizontal != NS_STYLE_OVERFLOW_VISIBLE &&
-               result.mHorizontal != NS_STYLE_OVERFLOW_CLIP &&
-               result.mVertical != NS_STYLE_OVERFLOW_VISIBLE &&
-               result.mVertical != NS_STYLE_OVERFLOW_CLIP,
-               "scrollbars should not have been created");
-  return result;
+  switch (overflow) {
+  case NS_STYLE_OVERFLOW_SCROLL:
+  case NS_STYLE_OVERFLOW_HIDDEN:
+  case NS_STYLE_OVERFLOW_VISIBLE: // should never happen
+  case NS_STYLE_OVERFLOW_AUTO:
+    return ScrollbarStyles(overflow, overflow);
+  case NS_STYLE_OVERFLOW_CLIP:
+    // This isn't quite right (although the value is deprecated and not
+    // very important). The scrollframe will still be scrollable using
+    // keys.  This can happen when HTML or BODY has propagated the style
+    // to the viewport.  (In other cases, there will be no scrollframe.)
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN, NS_STYLE_OVERFLOW_HIDDEN);
+  case NS_STYLE_OVERFLOW_SCROLLBARS_VERTICAL:
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN, NS_STYLE_OVERFLOW_SCROLL);
+  case NS_STYLE_OVERFLOW_SCROLLBARS_HORIZONTAL:
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN);
+  default:
+    NS_NOTREACHED("invalid overflow value");
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN, NS_STYLE_OVERFLOW_HIDDEN);
+  }
 }
 
 void
diff --git a/mozilla/layout/generic/nsIScrollableFrame.h b/mozilla/layout/generic/nsIScrollableFrame.h
index feb798e9210..6907cae2854 100644
--- a/mozilla/layout/generic/nsIScrollableFrame.h
+++ b/mozilla/layout/generic/nsIScrollableFrame.h
@@ -67,10 +67,10 @@ public:
 
   struct ScrollbarStyles {
     // one of NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN,
-    // NS_STYLE_OVERFLOW_AUTO
-    PRUint8 mHorizontal, mVertical;
-    ScrollbarStyles(PRUint8 h, PRUint8 v) : mHorizontal(h), mVertical(v) {}
-    ScrollbarStyles() {}
+    // NS_STYLE_OVERFLOW_VISIBLE, NS_STYLE_OVERFLOW_AUTO
+    PRInt32 mHorizontal;
+    PRInt32 mVertical;
+    ScrollbarStyles(PRInt32 h, PRInt32 v) : mHorizontal(h), mVertical(v) {}
   };
 
   virtual ScrollbarStyles GetScrollbarStyles() const = 0;
diff --git a/mozilla/layout/html/base/src/nsGfxScrollFrame.cpp b/mozilla/layout/html/base/src/nsGfxScrollFrame.cpp
index 00c7d8dc942..4608c28c76c 100644
--- a/mozilla/layout/html/base/src/nsGfxScrollFrame.cpp
+++ b/mozilla/layout/html/base/src/nsGfxScrollFrame.cpp
@@ -45,7 +45,6 @@
 #include "nsIServiceManager.h"
 #include "nsIView.h"
 #include "nsIScrollableView.h"
-#include "nsIScrollable.h"
 #include "nsIViewManager.h"
 #include "nsHTMLContainerFrame.h"
 #include "nsWidgetsCID.h"
@@ -1182,72 +1181,40 @@ NS_IMETHODIMP_(nsrefcnt) nsGfxScrollFrameInner::Release(void)
 
 NS_IMPL_QUERY_INTERFACE1(nsGfxScrollFrameInner, nsIScrollPositionListener)
 
-static void HandleScrollPref(nsIScrollable *aScrollable, PRInt32 aOrientation,
-                             PRUint8& aValue)
-{
-  PRInt32 pref;
-  aScrollable->GetDefaultScrollbarPreferences(aOrientation, &pref);
-  switch (pref) {
-    case nsIScrollable::Scrollbar_Auto:
-      // leave |aValue| untouched
-      break;
-    case nsIScrollable::Scrollbar_Never:
-      aValue = NS_STYLE_OVERFLOW_HIDDEN;
-      break;
-    case nsIScrollable::Scrollbar_Always:
-      aValue = NS_STYLE_OVERFLOW_SCROLL;
-      break;
-  }
-}
-
-static nsGfxScrollFrameInner::ScrollbarStyles
-ConvertOverflow(PRUint8 aOverflow)
-{
-  nsGfxScrollFrameInner::ScrollbarStyles result;
-  switch (aOverflow) {
-    case NS_STYLE_OVERFLOW_SCROLLBARS_VERTICAL:
-      result.mHorizontal = NS_STYLE_OVERFLOW_HIDDEN;
-      result.mVertical = NS_STYLE_OVERFLOW_SCROLL;
-      break;
-    case NS_STYLE_OVERFLOW_SCROLLBARS_HORIZONTAL:
-      result.mHorizontal = NS_STYLE_OVERFLOW_SCROLL;
-      result.mVertical = NS_STYLE_OVERFLOW_HIDDEN;
-      break;
-    default:
-      result.mHorizontal = aOverflow;
-      result.mVertical = aOverflow;
-  }
-  return result;
-}
-
 nsGfxScrollFrameInner::ScrollbarStyles
 nsGfxScrollFrameInner::GetScrollbarStylesFromFrame() const
 {
-  ScrollbarStyles result;
+  PRUint8 overflow;
   nsIFrame* parent = mOuter->GetParent();
   if (parent && parent->GetType() == nsLayoutAtoms::viewportFrame &&
       // Make sure we're actually the root scrollframe
       parent->GetFirstChild(nsnull) ==
         NS_STATIC_CAST(const nsIFrame*, mOuter)) {
-    nsPresContext *presContext = mOuter->GetPresContext();
-    result = ConvertOverflow(presContext->GetViewportOverflowOverride());
-
-    nsCOMPtr<nsISupports> container = presContext->GetContainer();
-    nsCOMPtr<nsIScrollable> scrollable = do_QueryInterface(container);
-    HandleScrollPref(scrollable, nsIScrollable::ScrollOrientation_X,
-                     result.mHorizontal);
-    HandleScrollPref(scrollable, nsIScrollable::ScrollOrientation_Y,
-                     result.mVertical);
+    overflow = mOuter->GetPresContext()->GetViewportOverflowOverride();
   } else {
-    result = ConvertOverflow(mOuter->GetStyleDisplay()->mOverflow);
+    overflow = mOuter->GetStyleDisplay()->mOverflow;
   }
 
-  NS_ASSERTION(result.mHorizontal != NS_STYLE_OVERFLOW_VISIBLE &&
-               result.mHorizontal != NS_STYLE_OVERFLOW_CLIP &&
-               result.mVertical != NS_STYLE_OVERFLOW_VISIBLE &&
-               result.mVertical != NS_STYLE_OVERFLOW_CLIP,
-               "scrollbars should not have been created");
-  return result;
+  switch (overflow) {
+  case NS_STYLE_OVERFLOW_SCROLL:
+  case NS_STYLE_OVERFLOW_HIDDEN:
+  case NS_STYLE_OVERFLOW_VISIBLE: // should never happen
+  case NS_STYLE_OVERFLOW_AUTO:
+    return ScrollbarStyles(overflow, overflow);
+  case NS_STYLE_OVERFLOW_CLIP:
+    // This isn't quite right (although the value is deprecated and not
+    // very important). The scrollframe will still be scrollable using
+    // keys.  This can happen when HTML or BODY has propagated the style
+    // to the viewport.  (In other cases, there will be no scrollframe.)
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN, NS_STYLE_OVERFLOW_HIDDEN);
+  case NS_STYLE_OVERFLOW_SCROLLBARS_VERTICAL:
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN, NS_STYLE_OVERFLOW_SCROLL);
+  case NS_STYLE_OVERFLOW_SCROLLBARS_HORIZONTAL:
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN);
+  default:
+    NS_NOTREACHED("invalid overflow value");
+    return ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN, NS_STYLE_OVERFLOW_HIDDEN);
+  }
 }
 
 void
diff --git a/mozilla/layout/html/style/src/nsCSSFrameConstructor.cpp b/mozilla/layout/html/style/src/nsCSSFrameConstructor.cpp
index a5c0948f6d3..1d484213ebb 100644
--- a/mozilla/layout/html/style/src/nsCSSFrameConstructor.cpp
+++ b/mozilla/layout/html/style/src/nsCSSFrameConstructor.cpp
@@ -3824,6 +3824,7 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIPresShell*        aPresShell,
   // for print-preview, but not when printing), then create a scroll frame that
   // will act as the scrolling mechanism for the viewport. 
   // XXX Do we even need a viewport when printing to a printer?
+  PRBool isScrollable = PR_TRUE;
 
   //isScrollable = PR_FALSE;
 
@@ -3836,6 +3837,8 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIPresShell*        aPresShell,
   //  2) NS_STYLE_OVERFLOW_AUTO = scrollbars appear if needed
   //  3) NS_STYLE_OVERFLOW_SCROLL = scrollbars always
   // Only need to create a scroll frame/view for cases 2 and 3.
+  // Currently OVERFLOW_SCROLL isn't honored, as
+  // scrollportview::SetScrollPref is not implemented.
 
   PRBool isHTML = aDocElement->IsContentOfType(nsIContent::eHTML);
   PRBool isXUL = PR_FALSE;
@@ -3845,13 +3848,28 @@ nsCSSFrameConstructor::ConstructRootFrame(nsIPresShell*        aPresShell,
   }
 
   // Never create scrollbars for XUL documents
-  PRBool isScrollable = !isXUL;
-
-  // Never create scrollbars for frameset documents.
-  if (isHTML) {
-    nsCOMPtr<nsIHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
-    if (htmlDoc && htmlDoc->GetIsFrameset())
-      isScrollable = PR_FALSE;
+#ifdef MOZ_XUL
+  if (isXUL) {
+    isScrollable = PR_FALSE;
+  } else 
+#endif
+  {
+    nsresult rv;
+    if (aPresContext) {
+      nsCOMPtr<nsISupports> container = aPresContext->GetContainer();
+      if (container) {
+        nsCOMPtr<nsIScrollable> scrollableContainer = do_QueryInterface(container, &rv);
+        if (NS_SUCCEEDED(rv) && scrollableContainer) {
+          PRInt32 scrolling = -1;
+          // XXX We should get prefs for X and Y and deal with these independently!
+          scrollableContainer->GetCurrentScrollbarPreferences(nsIScrollable::ScrollOrientation_Y,&scrolling);
+          if (nsIScrollable::Scrollbar_Never == scrolling) {
+            isScrollable = PR_FALSE;
+          }
+          // XXX NS_STYLE_OVERFLOW_SCROLL should create 'always on' scrollbars
+        }
+      }
+    }
   }
 
   if (isPaginated) {