diff --git a/content/base/public/nsIDocument.h b/content/base/public/nsIDocument.h
index 790bad506b7b..d290547b7f86 100644
--- a/content/base/public/nsIDocument.h
+++ b/content/base/public/nsIDocument.h
@@ -318,7 +318,8 @@ public:
   // notify that one or two content nodes changed state
   // either may be nsnull, but not both
   NS_IMETHOD ContentStatesChanged(nsIContent* aContent1,
-                                  nsIContent* aContent2) = 0;
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) = 0;
   NS_IMETHOD AttributeWillChange(nsIContent* aChild,
                                  PRInt32 aNameSpaceID,
                                  nsIAtom* aAttribute) = 0;
diff --git a/content/base/public/nsIDocumentObserver.h b/content/base/public/nsIDocumentObserver.h
index 4fc9217c1944..8b6741620dfb 100644
--- a/content/base/public/nsIDocumentObserver.h
+++ b/content/base/public/nsIDocumentObserver.h
@@ -138,7 +138,8 @@ public:
    */
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) = 0;
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) = 0;
 
   /**
    * Notification that the content model has changed. This method is called
diff --git a/content/base/public/nsIStyleRuleProcessor.h b/content/base/public/nsIStyleRuleProcessor.h
index e3558a8fe1ad..7079ad111cca 100644
--- a/content/base/public/nsIStyleRuleProcessor.h
+++ b/content/base/public/nsIStyleRuleProcessor.h
@@ -90,9 +90,10 @@ struct RuleProcessorData {
   PRPackedBool      mIsHTMLContent; // if content, then does QI on HTMLContent, true or false
   PRPackedBool      mIsHTMLLink;    // if content, calls nsStyleUtil::IsHTMLLink
   PRPackedBool      mIsSimpleXLink; // if content, calls nsStyleUtil::IsSimpleXLink
-  nsLinkState       mLinkState;     // if a link, this is the state, otherwise unknown
   PRPackedBool      mIsQuirkMode;   // Possibly remove use of this in SelectorMatches?
   PRPackedBool      mHasAttributes; // if content, content->GetAttrCount() > 0
+  PRPackedBool      mIsChecked;     // checked/selected attribute for option and select elements
+  nsLinkState       mLinkState;     // if a link, this is the state, otherwise unknown
   PRInt32           mEventState;    // if content, eventStateMgr->GetContentState()
   PRInt32           mNameSpaceID;   // if content, content->GetNameSapce()
   RuleProcessorData* mPreviousSiblingData;
diff --git a/content/base/src/nsContentList.h b/content/base/src/nsContentList.h
index bc58a7a0ebbf..9314e0ef0243 100644
--- a/content/base/src/nsContentList.h
+++ b/content/base/src/nsContentList.h
@@ -138,7 +138,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/content/base/src/nsDocument.cpp b/content/base/src/nsDocument.cpp
index 46d5cb82be12..5b5df264c340 100644
--- a/content/base/src/nsDocument.cpp
+++ b/content/base/src/nsDocument.cpp
@@ -1847,14 +1847,15 @@ nsDocument::ContentChanged(nsIContent* aContent,
 
 NS_IMETHODIMP
 nsDocument::ContentStatesChanged(nsIContent* aContent1,
-                                 nsIContent* aContent2)
+                                 nsIContent* aContent2,
+                                 nsIAtom* aChangedPseudoClass)
 {
   PRInt32 i;
   // Get new value of count for every iteration in case
   // observers remove themselves during the loop.
   for (i = 0; i < mObservers.Count(); i++) {
     nsIDocumentObserver*  observer = (nsIDocumentObserver*)mObservers[i];
-    observer->ContentStatesChanged(this, aContent1, aContent2);
+    observer->ContentStatesChanged(this, aContent1, aContent2, aChangedPseudoClass);
     // Make sure that the observer didn't remove itself during the
     // notification. If it did, update our index and count.
     if (i < mObservers.Count() &&
diff --git a/content/base/src/nsDocument.h b/content/base/src/nsDocument.h
index 0214ab38800b..cf77fee6871a 100644
--- a/content/base/src/nsDocument.h
+++ b/content/base/src/nsDocument.h
@@ -162,7 +162,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
@@ -452,7 +453,8 @@ public:
   NS_IMETHOD ContentChanged(nsIContent* aContent,
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
 
   NS_IMETHOD AttributeWillChange(nsIContent* aChild,
                                  PRInt32 aNameSpaceID,
diff --git a/content/base/src/nsStyleSet.cpp b/content/base/src/nsStyleSet.cpp
index ca9dc575c8b1..bb5d829263fe 100644
--- a/content/base/src/nsStyleSet.cpp
+++ b/content/base/src/nsStyleSet.cpp
@@ -206,7 +206,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIPresContext* aPresContext, 
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIPresContext*  aPresContext,
                               nsIContent* aChild,
                               PRInt32 aNameSpaceID,
@@ -1476,9 +1477,11 @@ StyleSetImpl::ContentChanged(nsIPresContext* aPresContext,
 NS_IMETHODIMP
 StyleSetImpl::ContentStatesChanged(nsIPresContext* aPresContext, 
                                    nsIContent* aContent1,
-                                   nsIContent* aContent2)
+                                   nsIContent* aContent2,
+                                   nsIAtom* aChangedPseudoClass)
 {
-  return mFrameConstructor->ContentStatesChanged(aPresContext, aContent1, aContent2);
+  return mFrameConstructor->ContentStatesChanged(aPresContext, aContent1, aContent2,
+                                                 aChangedPseudoClass);
 }
 
 
diff --git a/content/events/src/nsEventStateManager.cpp b/content/events/src/nsEventStateManager.cpp
index 5b6e87df775f..0e124cb62195 100644
--- a/content/events/src/nsEventStateManager.cpp
+++ b/content/events/src/nsEventStateManager.cpp
@@ -110,6 +110,7 @@
 #include "nsLayoutCID.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsUnicharUtils.h"
+#include "nsCSSAtoms.h"
 
 #if defined(DEBUG_rods) || defined(DEBUG_bryner)
 //#define DEBUG_DOCSHELL_FOCUS
@@ -3528,16 +3529,16 @@ nsEventStateManager::SetContentState(nsIContent *aContent, PRInt32 aState)
       if (newHover) {
         nsCOMPtr<nsIContent> parent;
         newHover->GetParent(*getter_AddRefs(parent));
-        doc1->ContentStatesChanged(newHover, parent);
+        doc1->ContentStatesChanged(newHover, parent, nsCSSAtoms::hoverPseudo);
         while (parent && parent != commonHoverParent) {
           parent->GetParent(*getter_AddRefs(newHover));
           if (newHover && newHover != commonHoverParent) {
             newHover->GetParent(*getter_AddRefs(parent));
             if (parent == commonHoverParent) {
-              doc1->ContentStatesChanged(newHover, nsnull);
+              doc1->ContentStatesChanged(newHover, nsnull, nsCSSAtoms::hoverPseudo);
             }
             else {
-              doc1->ContentStatesChanged(newHover, parent);
+              doc1->ContentStatesChanged(newHover, parent, nsCSSAtoms::hoverPseudo);
             }
           }
           else {
@@ -3549,16 +3550,16 @@ nsEventStateManager::SetContentState(nsIContent *aContent, PRInt32 aState)
       if (oldHover) {
         nsCOMPtr<nsIContent> parent;
         oldHover->GetParent(*getter_AddRefs(parent));
-        doc1->ContentStatesChanged(oldHover, parent);
+        doc1->ContentStatesChanged(oldHover, parent, nsCSSAtoms::hoverPseudo);
         while (parent && parent != commonHoverParent) {
           parent->GetParent(*getter_AddRefs(oldHover));
           if (oldHover && oldHover != commonHoverParent) {
             oldHover->GetParent(*getter_AddRefs(parent));
             if (parent == commonHoverParent) {
-              doc1->ContentStatesChanged(oldHover, nsnull);
+              doc1->ContentStatesChanged(oldHover, nsnull, nsCSSAtoms::hoverPseudo);
             }
             else {
-              doc1->ContentStatesChanged(oldHover, parent);
+              doc1->ContentStatesChanged(oldHover, parent, nsCSSAtoms::hoverPseudo);
             }
           }
           else {
@@ -3567,23 +3568,23 @@ nsEventStateManager::SetContentState(nsIContent *aContent, PRInt32 aState)
         }
       }
 
-      doc1->ContentStatesChanged(notifyContent[0], notifyContent[1]);
+      doc1->ContentStatesChanged(notifyContent[0], notifyContent[1], nsnull);
       if (notifyContent[2]) {  // more that two notifications are needed (should be rare)
         // XXX a further optimization here would be to group the notification pairs
         // together by parent/child, only needed if more than two content changed
         // (ie: if [0] and [2] are parent/child, then notify (0,2) (1,3))
-        doc1->ContentStatesChanged(notifyContent[2], notifyContent[3]);
+        doc1->ContentStatesChanged(notifyContent[2], notifyContent[3], nsnull);
         if (notifyContent[4]) {  // more that two notifications are needed (should be rare)
-          doc1->ContentStatesChanged(notifyContent[4], nsnull);
+          doc1->ContentStatesChanged(notifyContent[4], nsnull, nsnull);
         }
       }
       doc1->EndUpdate();
 
       if (doc2) {
         doc2->BeginUpdate();
-        doc2->ContentStatesChanged(notifyContent[1], notifyContent[2]);
+        doc2->ContentStatesChanged(notifyContent[1], notifyContent[2], nsnull);
         if (notifyContent[3]) {
-          doc1->ContentStatesChanged(notifyContent[3], notifyContent[4]);
+          doc1->ContentStatesChanged(notifyContent[3], notifyContent[4], nsnull);
         }
         doc2->EndUpdate();
       }
diff --git a/content/html/content/public/nsIOptionElement.h b/content/html/content/public/nsIOptionElement.h
index eb34de99d3e7..79af428be93e 100644
--- a/content/html/content/public/nsIOptionElement.h
+++ b/content/html/content/public/nsIOptionElement.h
@@ -60,13 +60,6 @@ public:
 
   NS_DEFINE_STATIC_IID_ACCESSOR(NS_IOPTIONELEMENT_IID)
 
-  /**
-   * Check whether the option element is selected from its own point
-   * of view.  This should only be used by SelectElement, really.
-   * Everyone else is safe using GetSelected() on the DOMHTMLOptionElement.
-   */
-  NS_IMETHOD GetSelectedInternal(PRBool* aValue) = 0;
-
   /**
    * Check whether the option element is selected from its own point
    * of view.  This should only be used by SelectElement, really.
diff --git a/content/html/content/src/nsHTMLOptionElement.cpp b/content/html/content/src/nsHTMLOptionElement.cpp
index a2d8607bf5ac..c0e0a72959df 100644
--- a/content/html/content/src/nsHTMLOptionElement.cpp
+++ b/content/html/content/src/nsHTMLOptionElement.cpp
@@ -68,7 +68,7 @@
 #include "nsNodeInfoManager.h"
 #include "nsCOMPtr.h"
 #include "nsLayoutAtoms.h"
-
+#include "nsCSSAtoms.h"
 
 class nsHTMLOptionElement : public nsGenericHTMLContainerElement,
                             public nsIDOMHTMLOptionElement,
@@ -108,7 +108,6 @@ public:
 #endif
 
   // nsIOptionElement
-  NS_IMETHOD GetSelectedInternal(PRBool* aValue);
   NS_IMETHOD SetSelectedInternal(PRBool aValue, PRBool aNotify);
   NS_IMETHOD GetValueOrText(nsAString& aValue);
 
@@ -121,7 +120,8 @@ protected:
   // there's a select associated with this option or not.
   void GetSelect(nsIDOMHTMLSelectElement **aSelectElement) const;
 
-  PRBool mIsInitialized;
+  PRPackedBool mIsInitialized;
+  PRPackedBool mIsSelected;
 };
 
 nsresult
@@ -170,8 +170,9 @@ NS_NewHTMLOptionElement(nsIHTMLContent** aInstancePtrResult,
 
 
 nsHTMLOptionElement::nsHTMLOptionElement()
+  : mIsInitialized(PR_FALSE),
+    mIsSelected(PR_FALSE)
 {
-  mIsInitialized = PR_FALSE;
 }
 
 nsHTMLOptionElement::~nsHTMLOptionElement()
@@ -241,43 +242,16 @@ nsHTMLOptionElement::GetForm(nsIDOMHTMLFormElement** aForm)
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsHTMLOptionElement::GetSelectedInternal(PRBool* aValue)
-{
-  // If it's not initialized, initialize it.
-  if (!mIsInitialized) {
-    mIsInitialized = PR_TRUE;
-    PRBool selected;
-    GetDefaultSelected(&selected);
-    // This does not need to be SetSelected (which sets selected in the select)
-    // because we *will* be initialized when we are placed into a select.  Plus
-    // it seems like that's just inviting an infinite loop.
-    SetSelectedInternal(selected, PR_TRUE);
-  }
-  nsAutoString tmpVal;
-  nsresult rv = GetAttr(kNameSpaceID_None,
-                        nsLayoutAtoms::optionSelectedPseudo,
-                        tmpVal);
-  *aValue = !(NS_FAILED(rv) || NS_CONTENT_ATTR_NOT_THERE == rv);
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsHTMLOptionElement::SetSelectedInternal(PRBool aValue, PRBool aNotify)
 {
   mIsInitialized = PR_TRUE;
+  mIsSelected = aValue;
 
-  // This affects the display, but what the hey, it's a good place for it
-  if (aValue) {
-    return SetAttr(kNameSpaceID_None,
-                   nsLayoutAtoms::optionSelectedPseudo,
-                   NS_LITERAL_STRING(""),
-                   aNotify);
-  } else {
-    return UnsetAttr(kNameSpaceID_None,
-                     nsLayoutAtoms::optionSelectedPseudo,
-                     aNotify);
-  }
+  if (aNotify && mDocument)
+    mDocument->ContentStatesChanged(this, nsnull, nsCSSAtoms::checkedPseudo);
+
+  return NS_OK;
 }
 
 NS_IMETHODIMP
@@ -309,8 +283,19 @@ nsHTMLOptionElement::GetSelected(PRBool* aValue)
   NS_ENSURE_ARG_POINTER(aValue);
   *aValue = PR_FALSE;
 
-  // If there is no select element, return the selected
-  return GetSelectedInternal(aValue);
+  // If it's not initialized, initialize it.
+  if (!mIsInitialized) {
+    mIsInitialized = PR_TRUE;
+    PRBool selected;
+    GetDefaultSelected(&selected);
+    // This does not need to be SetSelected (which sets selected in the select)
+    // because we *will* be initialized when we are placed into a select.  Plus
+    // it seems like that's just inviting an infinite loop.
+    SetSelectedInternal(selected, PR_TRUE);
+  }
+
+  *aValue = mIsSelected;
+  return NS_OK;
 }
 
 NS_IMETHODIMP
diff --git a/content/html/content/src/nsHTMLSelectElement.cpp b/content/html/content/src/nsHTMLSelectElement.cpp
index 9f2656b19ca4..ecaa541054d9 100644
--- a/content/html/content/src/nsHTMLSelectElement.cpp
+++ b/content/html/content/src/nsHTMLSelectElement.cpp
@@ -438,7 +438,7 @@ nsHTMLSelectElement::InsertOptionsIntoList(nsIContent* aOptions,
 
     // Actually select the options if the added options warrant it
     nsCOMPtr<nsIDOMNode> optionNode;
-    nsCOMPtr<nsIOptionElement> option;
+    nsCOMPtr<nsIDOMHTMLOptionElement> option;
     for (PRInt32 i=aListIndex;i<insertIndex;i++) {
       // Notify the frame that the option is added
       if (selectFrame) {
@@ -449,7 +449,7 @@ nsHTMLSelectElement::InsertOptionsIntoList(nsIContent* aOptions,
       option = do_QueryInterface(optionNode);
       if (option) {
         PRBool selected;
-        option->GetSelectedInternal(&selected);
+        option->GetSelected(&selected);
         if (selected) {
           // Clear all other options
           PRBool isMultiple;
diff --git a/content/html/document/src/nsHTMLContentSink.cpp b/content/html/document/src/nsHTMLContentSink.cpp
index 99c702bce8be..8693a5ff60de 100644
--- a/content/html/document/src/nsHTMLContentSink.cpp
+++ b/content/html/document/src/nsHTMLContentSink.cpp
@@ -290,7 +290,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/content/html/style/src/nsCSSStyleSheet.cpp b/content/html/style/src/nsCSSStyleSheet.cpp
index a5fe08851939..d5347bc050f6 100644
--- a/content/html/style/src/nsCSSStyleSheet.cpp
+++ b/content/html/style/src/nsCSSStyleSheet.cpp
@@ -70,6 +70,7 @@
 #include "nsIDOMHTMLAnchorElement.h"
 #include "nsIDOMHTMLLinkElement.h"
 #include "nsIDOMHTMLAreaElement.h"
+#include "nsIDOMHTMLOptionElement.h"
 #include "nsIDOMStyleSheetList.h"
 #include "nsIDOMCSSStyleSheet.h"
 #include "nsIDOMCSSStyleRule.h"
@@ -3232,6 +3233,7 @@ RuleProcessorData::RuleProcessorData(nsIPresContext* aPresContext,
   mIsHTMLContent = PR_FALSE;
   mIsHTMLLink = PR_FALSE;
   mIsSimpleXLink = PR_FALSE;
+  mIsChecked = PR_FALSE;
   mLinkState = eLinkState_Unknown;
   mEventState = NS_EVENT_STATE_UNSPECIFIED;
   mNameSpaceID = kNameSpaceID_Unknown;
@@ -3299,6 +3301,15 @@ RuleProcessorData::RuleProcessorData(nsIPresContext* aPresContext,
        nsStyleUtil::IsSimpleXlink(aContent, mPresContext, &mLinkState)) {
       mIsSimpleXLink = PR_TRUE;
     } 
+
+    if (mIsHTMLContent) {
+      PRBool isChecked = PR_FALSE;
+      if (mContentTag == nsHTMLAtoms::option) {
+        nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(mContent);
+        optEl->GetSelected(&isChecked);
+      }
+      mIsChecked = isChecked;
+    }
   }
 }
 
@@ -3590,6 +3601,14 @@ static PRBool SelectorMatches(RuleProcessorData &data,
           result = localFalse;  // not a link
         }
       }
+      else if (nsCSSAtoms::checkedPseudo == pseudoClass->mAtom) {
+        // This pseudoclass matches the selected state on the following elements:
+        //  <option>
+        //  <input type=checkbox>
+        //  <input type=radio>
+        if (aTestState)
+          result = data.mIsChecked ? localTrue : localFalse;
+      }
       else {
         result = localFalse;  // unknown pseudo class
       }
diff --git a/content/shared/public/nsLayoutAtomList.h b/content/shared/public/nsLayoutAtomList.h
index c5616cce6b53..e9d8760ee788 100644
--- a/content/shared/public/nsLayoutAtomList.h
+++ b/content/shared/public/nsLayoutAtomList.h
@@ -87,7 +87,6 @@ LAYOUT_ATOM(popupList, "Popup-list")
 LAYOUT_ATOM(canvasPseudo, ":canvas")
 LAYOUT_ATOM(commentTagName, "__moz_comment")
 LAYOUT_ATOM(dummyOptionPseudo, ":-moz-dummy-option")
-LAYOUT_ATOM(optionSelectedPseudo, "_moz-option-selected")
 LAYOUT_ATOM(textTagName, "__moz_text")
 LAYOUT_ATOM(pagePseudo, ":-moz-page")
 LAYOUT_ATOM(pageContentPseudo, ":-moz-pagecontent")
diff --git a/content/xbl/src/nsBindingManager.cpp b/content/xbl/src/nsBindingManager.cpp
index 67dc15b121a8..9fd1214ac1af 100644
--- a/content/xbl/src/nsBindingManager.cpp
+++ b/content/xbl/src/nsBindingManager.cpp
@@ -304,7 +304,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD AttributeChanged(nsIDocument* aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/content/xul/document/src/nsXULDocument.cpp b/content/xul/document/src/nsXULDocument.cpp
index 4a31e6239122..eab699c406f1 100644
--- a/content/xul/document/src/nsXULDocument.cpp
+++ b/content/xul/document/src/nsXULDocument.cpp
@@ -1933,11 +1933,13 @@ nsXULDocument::ContentChanged(nsIContent* aContent,
 }
 
 NS_IMETHODIMP
-nsXULDocument::ContentStatesChanged(nsIContent* aContent1, nsIContent* aContent2)
+nsXULDocument::ContentStatesChanged(nsIContent* aContent1,
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudoClass)
 {
     for (PRInt32 i = mObservers.Count() - 1; i >= 0; --i) {
         nsIDocumentObserver*  observer = (nsIDocumentObserver*)mObservers[i];
-        observer->ContentStatesChanged(this, aContent1, aContent2);
+        observer->ContentStatesChanged(this, aContent1, aContent2, aChangedPseudoClass);
     }
     return NS_OK;
 }
diff --git a/content/xul/document/src/nsXULDocument.h b/content/xul/document/src/nsXULDocument.h
index 4515b596a351..ccf64d67df70 100644
--- a/content/xul/document/src/nsXULDocument.h
+++ b/content/xul/document/src/nsXULDocument.h
@@ -278,7 +278,9 @@ public:
     NS_IMETHOD ContentChanged(nsIContent* aContent,
                               nsISupports* aSubContent);
 
-    NS_IMETHOD ContentStatesChanged(nsIContent* aContent1, nsIContent* aContent2);
+    NS_IMETHOD ContentStatesChanged(nsIContent* aContent1,
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudoClass);
 
     NS_IMETHOD AttributeChanged(nsIContent* aChild,
                                 PRInt32 aNameSpaceID,
diff --git a/content/xul/templates/src/nsXULTemplateBuilder.cpp b/content/xul/templates/src/nsXULTemplateBuilder.cpp
index cdda4e165160..6d675751772e 100644
--- a/content/xul/templates/src/nsXULTemplateBuilder.cpp
+++ b/content/xul/templates/src/nsXULTemplateBuilder.cpp
@@ -337,7 +337,8 @@ nsXULTemplateBuilder::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 nsXULTemplateBuilder::ContentStatesChanged(nsIDocument* aDocument,
                                            nsIContent* aContent1,
-                                           nsIContent* aContent2)
+                                           nsIContent* aContent2,
+                                           nsIAtom* aChangedPseudoClass)
 {
     return NS_OK;
 }
diff --git a/content/xul/templates/src/nsXULTemplateBuilder.h b/content/xul/templates/src/nsXULTemplateBuilder.h
index 001090eb167d..2fe5bf00e98e 100644
--- a/content/xul/templates/src/nsXULTemplateBuilder.h
+++ b/content/xul/templates/src/nsXULTemplateBuilder.h
@@ -115,7 +115,8 @@ public:
 
     NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                     nsIContent* aContent1,
-                                    nsIContent* aContent2);
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudoClass);
 
     NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                                 nsIContent*  aContent,
diff --git a/extensions/inspector/base/src/inDOMView.h b/extensions/inspector/base/src/inDOMView.h
index 6cebaf7337bd..559685739506 100644
--- a/extensions/inspector/base/src/inDOMView.h
+++ b/extensions/inspector/base/src/inDOMView.h
@@ -91,7 +91,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+				  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD BeginUpdate(nsIDocument *aDocument) { return NS_OK; }
   NS_IMETHOD EndUpdate(nsIDocument *aDocument) { return NS_OK; }
   NS_IMETHOD BeginLoad(nsIDocument *aDocument) { return NS_OK; }
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index d066e1e5940c..a2e7b4d0f756 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -10064,7 +10064,8 @@ nsCSSFrameConstructor::ProcessRestyledFrames(nsStyleChangeList& aChangeList,
 NS_IMETHODIMP
 nsCSSFrameConstructor::ContentStatesChanged(nsIPresContext* aPresContext, 
                                             nsIContent* aContent1,
-                                            nsIContent* aContent2)
+                                            nsIContent* aContent2,
+                                            nsIAtom* aChangedPseudoClass)
 {
   nsresult  result = NS_OK;
 
diff --git a/layout/base/nsCSSFrameConstructor.h b/layout/base/nsCSSFrameConstructor.h
index d444a3080309..b3d9087a5761 100644
--- a/layout/base/nsCSSFrameConstructor.h
+++ b/layout/base/nsCSSFrameConstructor.h
@@ -122,7 +122,8 @@ public:
 
   NS_IMETHOD ContentStatesChanged(nsIPresContext* aPresContext, 
                                   nsIContent*     aContent1,
-                                  nsIContent*     aContent2);
+                                  nsIContent*     aContent2,
+                                  nsIAtom*        aChangedPseudoClass);
 
   NS_IMETHOD AttributeChanged(nsIPresContext* aPresContext,
                               nsIContent*     aContent,
diff --git a/layout/base/nsLayoutAtomList.h b/layout/base/nsLayoutAtomList.h
index c5616cce6b53..e9d8760ee788 100644
--- a/layout/base/nsLayoutAtomList.h
+++ b/layout/base/nsLayoutAtomList.h
@@ -87,7 +87,6 @@ LAYOUT_ATOM(popupList, "Popup-list")
 LAYOUT_ATOM(canvasPseudo, ":canvas")
 LAYOUT_ATOM(commentTagName, "__moz_comment")
 LAYOUT_ATOM(dummyOptionPseudo, ":-moz-dummy-option")
-LAYOUT_ATOM(optionSelectedPseudo, "_moz-option-selected")
 LAYOUT_ATOM(textTagName, "__moz_text")
 LAYOUT_ATOM(pagePseudo, ":-moz-page")
 LAYOUT_ATOM(pageContentPseudo, ":-moz-pagecontent")
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 4b2fde07a43f..445cc7930fcd 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -1028,7 +1028,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
@@ -5095,10 +5096,12 @@ PresShell::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 PresShell::ContentStatesChanged(nsIDocument* aDocument,
                                 nsIContent* aContent1,
-                                nsIContent* aContent2)
+                                nsIContent* aContent2,
+                                nsIAtom* aChangedPseudoClass)
 {
   WillCauseReflow();
-  nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2);
+  nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2,
+                                                aChangedPseudoClass);
   VERIFY_STYLE_TREE;
   DidCauseReflow();
 
diff --git a/layout/base/public/nsIStyleFrameConstruction.h b/layout/base/public/nsIStyleFrameConstruction.h
index ed678eb6bb6a..3a0db268fa9f 100644
--- a/layout/base/public/nsIStyleFrameConstruction.h
+++ b/layout/base/public/nsIStyleFrameConstruction.h
@@ -202,7 +202,8 @@ public:
     */
   NS_IMETHOD ContentStatesChanged(nsIPresContext* aPresContext, 
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) = 0;
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) = 0;
 
   /**
     * Notification that an attribute was changed for a content node
diff --git a/layout/base/public/nsIStyleSet.h b/layout/base/public/nsIStyleSet.h
index e0359c2711a3..8684790e4316 100644
--- a/layout/base/public/nsIStyleSet.h
+++ b/layout/base/public/nsIStyleSet.h
@@ -229,7 +229,8 @@ public:
                             nsISupports* aSubContent) = 0;
   NS_IMETHOD ContentStatesChanged(nsIPresContext* aPresContext, 
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) = 0;
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) = 0;
   NS_IMETHOD AttributeChanged(nsIPresContext*  aPresContext,
                               nsIContent* aChild,
                               PRInt32 aNameSpaceID,
diff --git a/layout/forms/nsListControlFrame.cpp b/layout/forms/nsListControlFrame.cpp
index 7a8d4d9ccd90..9b7c9e1f695f 100644
--- a/layout/forms/nsListControlFrame.cpp
+++ b/layout/forms/nsListControlFrame.cpp
@@ -93,11 +93,7 @@ const PRInt32 kNothingSelected          = -1;
 const PRInt32 kMaxZ                     = 0x7fffffff; //XXX: Shouldn't there be a define somewhere for MaxInt for PRInt32
 const PRInt32 kNoSizeSpecified          = -1;
 
-//XXX: This is temporary. It simulates psuedo states by using a attribute selector on 
-// -moz-option-selected in the ua.css style sheet. This will not be needed when
-//The event state manager is functional. KMM
-//const char * kMozSelected = "-moz-option-selected";
-// it is now using "nsLayoutAtoms::optionSelectedPseudo"
+// We now use the :checked pseudoclass for the option selected state
 
 //---------------------------------------------------------
 nsresult
@@ -1678,11 +1674,13 @@ nsListControlFrame::GetOption(nsIDOMHTMLCollection& aCollection, PRInt32 aIndex)
 PRBool 
 nsListControlFrame::IsContentSelected(nsIContent* aContent)
 {
-  nsAutoString value;
-  //nsIAtom * selectedAtom = NS_NewAtom("selected");
-  nsresult result = aContent->GetAttr(kNameSpaceID_None, nsLayoutAtoms::optionSelectedPseudo, value);
+  PRBool isSelected = PR_FALSE;
 
-  return (NS_CONTENT_ATTR_NOT_THERE == result ? PR_FALSE : PR_TRUE);
+  nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(aContent);
+  if (optEl)
+    optEl->GetSelected(&isSelected);
+
+  return isSelected;
 }
 
 
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index 0c5bff9df0b1..df9987b4d6e4 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -104,7 +104,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/layout/generic/nsImageMap.cpp b/layout/generic/nsImageMap.cpp
index 3337ccff8a15..6c5b356b4eff 100644
--- a/layout/generic/nsImageMap.cpp
+++ b/layout/generic/nsImageMap.cpp
@@ -1116,7 +1116,8 @@ nsImageMap::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 nsImageMap::ContentStatesChanged(nsIDocument* aDocument,
                                  nsIContent* aContent1,
-                                 nsIContent* aContent2)
+                                 nsIContent* aContent2,
+                                 nsIAtom* aChangedPseudoClass)
 {
   return NS_OK;
 }
diff --git a/layout/generic/nsImageMap.h b/layout/generic/nsImageMap.h
index f96bfb84d58e..9b755174748f 100644
--- a/layout/generic/nsImageMap.h
+++ b/layout/generic/nsImageMap.h
@@ -108,7 +108,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/layout/html/base/src/nsGfxScrollFrame.cpp b/layout/html/base/src/nsGfxScrollFrame.cpp
index 0c5bff9df0b1..df9987b4d6e4 100644
--- a/layout/html/base/src/nsGfxScrollFrame.cpp
+++ b/layout/html/base/src/nsGfxScrollFrame.cpp
@@ -104,7 +104,8 @@ public:
                             nsISupports* aSubContent) { return NS_OK; }
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2) { return NS_OK; }
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass) { return NS_OK; }
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/layout/html/base/src/nsImageMap.cpp b/layout/html/base/src/nsImageMap.cpp
index 3337ccff8a15..6c5b356b4eff 100644
--- a/layout/html/base/src/nsImageMap.cpp
+++ b/layout/html/base/src/nsImageMap.cpp
@@ -1116,7 +1116,8 @@ nsImageMap::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 nsImageMap::ContentStatesChanged(nsIDocument* aDocument,
                                  nsIContent* aContent1,
-                                 nsIContent* aContent2)
+                                 nsIContent* aContent2,
+                                 nsIAtom* aChangedPseudoClass)
 {
   return NS_OK;
 }
diff --git a/layout/html/base/src/nsImageMap.h b/layout/html/base/src/nsImageMap.h
index f96bfb84d58e..9b755174748f 100644
--- a/layout/html/base/src/nsImageMap.h
+++ b/layout/html/base/src/nsImageMap.h
@@ -108,7 +108,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/layout/html/base/src/nsPresShell.cpp b/layout/html/base/src/nsPresShell.cpp
index 4b2fde07a43f..445cc7930fcd 100644
--- a/layout/html/base/src/nsPresShell.cpp
+++ b/layout/html/base/src/nsPresShell.cpp
@@ -1028,7 +1028,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
@@ -5095,10 +5096,12 @@ PresShell::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 PresShell::ContentStatesChanged(nsIDocument* aDocument,
                                 nsIContent* aContent1,
-                                nsIContent* aContent2)
+                                nsIContent* aContent2,
+                                nsIAtom* aChangedPseudoClass)
 {
   WillCauseReflow();
-  nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2);
+  nsresult rv = mStyleSet->ContentStatesChanged(mPresContext, aContent1, aContent2,
+                                                aChangedPseudoClass);
   VERIFY_STYLE_TREE;
   DidCauseReflow();
 
diff --git a/layout/html/document/src/forms.css b/layout/html/document/src/forms.css
index 4e94c8c15a1e..8d6e82c90db0 100644
--- a/layout/html/document/src/forms.css
+++ b/layout/html/document/src/forms.css
@@ -181,7 +181,7 @@ select > option {
   padding: 0 5px 0 3px;
 }
 
-option[_moz-option-selected] {
+option:checked {
   color: HighlightText ! important;
   background-color: Highlight ! important;
 }
diff --git a/layout/html/forms/src/nsListControlFrame.cpp b/layout/html/forms/src/nsListControlFrame.cpp
index 7a8d4d9ccd90..9b7c9e1f695f 100644
--- a/layout/html/forms/src/nsListControlFrame.cpp
+++ b/layout/html/forms/src/nsListControlFrame.cpp
@@ -93,11 +93,7 @@ const PRInt32 kNothingSelected          = -1;
 const PRInt32 kMaxZ                     = 0x7fffffff; //XXX: Shouldn't there be a define somewhere for MaxInt for PRInt32
 const PRInt32 kNoSizeSpecified          = -1;
 
-//XXX: This is temporary. It simulates psuedo states by using a attribute selector on 
-// -moz-option-selected in the ua.css style sheet. This will not be needed when
-//The event state manager is functional. KMM
-//const char * kMozSelected = "-moz-option-selected";
-// it is now using "nsLayoutAtoms::optionSelectedPseudo"
+// We now use the :checked pseudoclass for the option selected state
 
 //---------------------------------------------------------
 nsresult
@@ -1678,11 +1674,13 @@ nsListControlFrame::GetOption(nsIDOMHTMLCollection& aCollection, PRInt32 aIndex)
 PRBool 
 nsListControlFrame::IsContentSelected(nsIContent* aContent)
 {
-  nsAutoString value;
-  //nsIAtom * selectedAtom = NS_NewAtom("selected");
-  nsresult result = aContent->GetAttr(kNameSpaceID_None, nsLayoutAtoms::optionSelectedPseudo, value);
+  PRBool isSelected = PR_FALSE;
 
-  return (NS_CONTENT_ATTR_NOT_THERE == result ? PR_FALSE : PR_TRUE);
+  nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(aContent);
+  if (optEl)
+    optEl->GetSelected(&isSelected);
+
+  return isSelected;
 }
 
 
diff --git a/layout/html/style/src/nsCSSFrameConstructor.cpp b/layout/html/style/src/nsCSSFrameConstructor.cpp
index d066e1e5940c..a2e7b4d0f756 100644
--- a/layout/html/style/src/nsCSSFrameConstructor.cpp
+++ b/layout/html/style/src/nsCSSFrameConstructor.cpp
@@ -10064,7 +10064,8 @@ nsCSSFrameConstructor::ProcessRestyledFrames(nsStyleChangeList& aChangeList,
 NS_IMETHODIMP
 nsCSSFrameConstructor::ContentStatesChanged(nsIPresContext* aPresContext, 
                                             nsIContent* aContent1,
-                                            nsIContent* aContent2)
+                                            nsIContent* aContent2,
+                                            nsIAtom* aChangedPseudoClass)
 {
   nsresult  result = NS_OK;
 
diff --git a/layout/html/style/src/nsCSSFrameConstructor.h b/layout/html/style/src/nsCSSFrameConstructor.h
index d444a3080309..b3d9087a5761 100644
--- a/layout/html/style/src/nsCSSFrameConstructor.h
+++ b/layout/html/style/src/nsCSSFrameConstructor.h
@@ -122,7 +122,8 @@ public:
 
   NS_IMETHOD ContentStatesChanged(nsIPresContext* aPresContext, 
                                   nsIContent*     aContent1,
-                                  nsIContent*     aContent2);
+                                  nsIContent*     aContent2,
+                                  nsIAtom*        aChangedPseudoClass);
 
   NS_IMETHOD AttributeChanged(nsIPresContext* aPresContext,
                               nsIContent*     aContent,
diff --git a/layout/style/forms.css b/layout/style/forms.css
index 4e94c8c15a1e..8d6e82c90db0 100644
--- a/layout/style/forms.css
+++ b/layout/style/forms.css
@@ -181,7 +181,7 @@ select > option {
   padding: 0 5px 0 3px;
 }
 
-option[_moz-option-selected] {
+option:checked {
   color: HighlightText ! important;
   background-color: Highlight ! important;
 }
diff --git a/layout/style/nsCSSStyleSheet.cpp b/layout/style/nsCSSStyleSheet.cpp
index a5fe08851939..d5347bc050f6 100644
--- a/layout/style/nsCSSStyleSheet.cpp
+++ b/layout/style/nsCSSStyleSheet.cpp
@@ -70,6 +70,7 @@
 #include "nsIDOMHTMLAnchorElement.h"
 #include "nsIDOMHTMLLinkElement.h"
 #include "nsIDOMHTMLAreaElement.h"
+#include "nsIDOMHTMLOptionElement.h"
 #include "nsIDOMStyleSheetList.h"
 #include "nsIDOMCSSStyleSheet.h"
 #include "nsIDOMCSSStyleRule.h"
@@ -3232,6 +3233,7 @@ RuleProcessorData::RuleProcessorData(nsIPresContext* aPresContext,
   mIsHTMLContent = PR_FALSE;
   mIsHTMLLink = PR_FALSE;
   mIsSimpleXLink = PR_FALSE;
+  mIsChecked = PR_FALSE;
   mLinkState = eLinkState_Unknown;
   mEventState = NS_EVENT_STATE_UNSPECIFIED;
   mNameSpaceID = kNameSpaceID_Unknown;
@@ -3299,6 +3301,15 @@ RuleProcessorData::RuleProcessorData(nsIPresContext* aPresContext,
        nsStyleUtil::IsSimpleXlink(aContent, mPresContext, &mLinkState)) {
       mIsSimpleXLink = PR_TRUE;
     } 
+
+    if (mIsHTMLContent) {
+      PRBool isChecked = PR_FALSE;
+      if (mContentTag == nsHTMLAtoms::option) {
+        nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(mContent);
+        optEl->GetSelected(&isChecked);
+      }
+      mIsChecked = isChecked;
+    }
   }
 }
 
@@ -3590,6 +3601,14 @@ static PRBool SelectorMatches(RuleProcessorData &data,
           result = localFalse;  // not a link
         }
       }
+      else if (nsCSSAtoms::checkedPseudo == pseudoClass->mAtom) {
+        // This pseudoclass matches the selected state on the following elements:
+        //  <option>
+        //  <input type=checkbox>
+        //  <input type=radio>
+        if (aTestState)
+          result = data.mIsChecked ? localTrue : localFalse;
+      }
       else {
         result = localFalse;  // unknown pseudo class
       }
diff --git a/layout/style/nsIStyleRuleProcessor.h b/layout/style/nsIStyleRuleProcessor.h
index e3558a8fe1ad..7079ad111cca 100644
--- a/layout/style/nsIStyleRuleProcessor.h
+++ b/layout/style/nsIStyleRuleProcessor.h
@@ -90,9 +90,10 @@ struct RuleProcessorData {
   PRPackedBool      mIsHTMLContent; // if content, then does QI on HTMLContent, true or false
   PRPackedBool      mIsHTMLLink;    // if content, calls nsStyleUtil::IsHTMLLink
   PRPackedBool      mIsSimpleXLink; // if content, calls nsStyleUtil::IsSimpleXLink
-  nsLinkState       mLinkState;     // if a link, this is the state, otherwise unknown
   PRPackedBool      mIsQuirkMode;   // Possibly remove use of this in SelectorMatches?
   PRPackedBool      mHasAttributes; // if content, content->GetAttrCount() > 0
+  PRPackedBool      mIsChecked;     // checked/selected attribute for option and select elements
+  nsLinkState       mLinkState;     // if a link, this is the state, otherwise unknown
   PRInt32           mEventState;    // if content, eventStateMgr->GetContentState()
   PRInt32           mNameSpaceID;   // if content, content->GetNameSapce()
   RuleProcessorData* mPreviousSiblingData;
diff --git a/layout/style/nsStyleSet.cpp b/layout/style/nsStyleSet.cpp
index ca9dc575c8b1..bb5d829263fe 100644
--- a/layout/style/nsStyleSet.cpp
+++ b/layout/style/nsStyleSet.cpp
@@ -206,7 +206,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIPresContext* aPresContext, 
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIPresContext*  aPresContext,
                               nsIContent* aChild,
                               PRInt32 aNameSpaceID,
@@ -1476,9 +1477,11 @@ StyleSetImpl::ContentChanged(nsIPresContext* aPresContext,
 NS_IMETHODIMP
 StyleSetImpl::ContentStatesChanged(nsIPresContext* aPresContext, 
                                    nsIContent* aContent1,
-                                   nsIContent* aContent2)
+                                   nsIContent* aContent2,
+                                   nsIAtom* aChangedPseudoClass)
 {
-  return mFrameConstructor->ContentStatesChanged(aPresContext, aContent1, aContent2);
+  return mFrameConstructor->ContentStatesChanged(aPresContext, aContent1, aContent2,
+                                                 aChangedPseudoClass);
 }
 
 
diff --git a/layout/xul/base/src/outliner/src/nsOutlinerContentView.cpp b/layout/xul/base/src/outliner/src/nsOutlinerContentView.cpp
index df7c4861f0c4..86ba4d04231a 100644
--- a/layout/xul/base/src/outliner/src/nsOutlinerContentView.cpp
+++ b/layout/xul/base/src/outliner/src/nsOutlinerContentView.cpp
@@ -41,6 +41,7 @@
 #include "nsINameSpaceManager.h"
 #include "nsHTMLAtoms.h"
 #include "nsXULAtoms.h"
+#include "nsCSSAtoms.h"
 #include "nsLayoutAtoms.h"
 #include "nsIDOMDocument.h"
 #include "nsIBoxObject.h"
@@ -221,8 +222,13 @@ nsOutlinerContentView::SetSelection(nsIOutlinerSelection* aSelection)
     mSelection->SetSelectEventsSuppressed(PR_TRUE);
     for (PRInt32 i = 0; i < mRows.Count(); ++i) {
       Row* row = (Row*)mRows[i];
-      if (row->mContent->HasAttr(kNameSpaceID_None, nsLayoutAtoms::optionSelectedPseudo))
-        mSelection->ToggleSelect(i);
+      nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(row->mContent);
+      if (optEl) {
+        PRBool isSelected;
+        optEl->GetSelected(&isSelected);
+        if (isSelected)
+          mSelection->ToggleSelect(i);
+      }
     }
     mSelection->SetSelectEventsSuppressed(PR_FALSE);
   }
@@ -648,8 +654,22 @@ nsOutlinerContentView::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 nsOutlinerContentView::ContentStatesChanged(nsIDocument* aDocument,
                                            nsIContent* aContent1,
-                                           nsIContent* aContent2)
+                                           nsIContent* aContent2,
+                                           nsIAtom* aChangedPseudoClass)
 {
+  if (!aContent1 || !mSelection || !aContent1->IsContentOfType(nsIContent::eHTML) ||
+      aChangedPseudoClass != nsCSSAtoms::checkedPseudo)
+    return NS_OK;
+        
+  nsCOMPtr<nsIAtom> contentTag;
+  aContent1->GetTag(*getter_AddRefs(contentTag));   
+  if (contentTag == nsHTMLAtoms::option) {
+    // update the selected state for this node
+    PRInt32 index = FindContent(aContent1);
+    if (index >= 0)
+      mSelection->ToggleSelect(index);
+  }
+  
   return NS_OK;
 }
 
@@ -663,6 +683,10 @@ nsOutlinerContentView::AttributeChanged(nsIDocument *aDocument,
 {
   // First, get the element on which the attribute has changed
   // and then try to find content item in our array of rows.
+
+  if (!aContent->IsContentOfType(nsIContent::eXUL))
+    return NS_OK;
+
   nsCOMPtr<nsIAtom> tag;
   aContent->GetTag(*getter_AddRefs(tag));
 
@@ -734,16 +758,6 @@ nsOutlinerContentView::AttributeChanged(nsIDocument *aDocument,
       }
     }
   }
-  else if (tag == nsHTMLAtoms::option) {
-    if (aAttribute == nsLayoutAtoms::optionSelectedPseudo) {
-      PRInt32 index = FindContent(aContent);
-      if (index >= 0) {
-        NS_ASSERTION(mSelection, "Need to handle optionSelected change with no OutlinerSelection");
-        if (mSelection)
-          mSelection->ToggleSelect(index);
-      }
-    }
-  }
 
   return NS_OK;
 }
@@ -771,12 +785,17 @@ nsOutlinerContentView::ContentInserted(nsIDocument *aDocument,
   nsCOMPtr<nsIAtom> childTag;
   aChild->GetTag(*getter_AddRefs(childTag));
 
-  if ((childTag != nsXULAtoms::outlineritem) &&
-      (childTag != nsXULAtoms::outlinerseparator) &&
-      (childTag != nsHTMLAtoms::option) &&
-      (childTag != nsXULAtoms::outlinerchildren) &&
-      (childTag != nsXULAtoms::outlinerrow) &&
-      (childTag != nsXULAtoms::outlinercell))
+  if (aChild->IsContentOfType(nsIContent::eHTML)) {
+    if (childTag != nsHTMLAtoms::option)
+      return NS_OK;
+  } else if (aChild->IsContentOfType(nsIContent::eXUL)) {
+    if (childTag != nsXULAtoms::outlineritem &&
+        childTag != nsXULAtoms::outlinerseparator &&
+        childTag != nsXULAtoms::outlinerchildren &&
+        childTag != nsXULAtoms::outlinerrow &&
+        childTag != nsXULAtoms::outlinercell)
+      return NS_OK;
+  } else
     return NS_OK;
 
   // If we have a legal tag, go up to the outliner/select and make sure
@@ -786,7 +805,8 @@ nsOutlinerContentView::ContentInserted(nsIDocument *aDocument,
   
   while (element) {
     element->GetTag(*getter_AddRefs(parentTag));
-    if (parentTag == nsXULAtoms::outliner || parentTag == nsHTMLAtoms::select)
+    if ((element->IsContentOfType(nsIContent::eXUL) && parentTag == nsXULAtoms::outliner) ||
+        (element->IsContentOfType(nsIContent::eHTML) && parentTag == nsHTMLAtoms::select))
       if (element == mRoot) // this is for us, stop looking
         break;
       else // this is not for us, we can bail out
@@ -874,12 +894,17 @@ nsOutlinerContentView::ContentRemoved(nsIDocument *aDocument,
   nsCOMPtr<nsIAtom> tag;
   aChild->GetTag(*getter_AddRefs(tag));
 
-  if ((tag != nsXULAtoms::outlineritem) &&
-      (tag != nsXULAtoms::outlinerseparator) &&
-      (tag != nsHTMLAtoms::option) &&
-      (tag != nsXULAtoms::outlinerchildren) &&
-      (tag != nsXULAtoms::outlinerrow) &&
-      (tag != nsXULAtoms::outlinercell))
+  if (aChild->IsContentOfType(nsIContent::eHTML)) {
+    if (tag != nsHTMLAtoms::option)
+      return NS_OK;
+  } else if (aChild->IsContentOfType(nsIContent::eXUL)) {
+    if (tag != nsXULAtoms::outlineritem &&
+        tag != nsXULAtoms::outlinerseparator &&
+        tag != nsXULAtoms::outlinerchildren &&
+        tag != nsXULAtoms::outlinerrow &&
+        tag != nsXULAtoms::outlinercell)
+      return NS_OK;
+  } else
     return NS_OK;
 
   // If we have a legal tag, go up to the outliner/select and make sure
@@ -889,7 +914,8 @@ nsOutlinerContentView::ContentRemoved(nsIDocument *aDocument,
   
   while (element) {
     element->GetTag(*getter_AddRefs(parentTag));
-    if (parentTag == nsXULAtoms::outliner || parentTag == nsHTMLAtoms::select)
+    if ((element->IsContentOfType(nsIContent::eXUL) && parentTag == nsXULAtoms::outliner) || 
+        (element->IsContentOfType(nsIContent::eHTML) && parentTag == nsHTMLAtoms::select))
       if (element == mRoot) // this is for us, stop looking
         break;
       else // this is not for us, we can bail out
@@ -1010,12 +1036,15 @@ nsOutlinerContentView::Serialize(nsIContent* aContent, PRInt32 aParentIndex, PRI
     nsCOMPtr<nsIAtom> tag;
     content->GetTag(*getter_AddRefs(tag));
     PRInt32 count = aRows.Count();
-    if (tag == nsXULAtoms::outlineritem)
-      SerializeItem(content, aParentIndex, aIndex, aRows);
-    else if (tag == nsXULAtoms::outlinerseparator)
-      SerializeSeparator(content, aParentIndex, aIndex, aRows);
-    else if (tag == nsHTMLAtoms::option)
-      SerializeOption(content, aParentIndex, aIndex, aRows);
+    if (content->IsContentOfType(nsIContent::eXUL)) {
+      if (tag == nsXULAtoms::outlineritem)
+        SerializeItem(content, aParentIndex, aIndex, aRows);
+      else if (tag == nsXULAtoms::outlinerseparator)
+        SerializeSeparator(content, aParentIndex, aIndex, aRows);
+    } else if (content->IsContentOfType(nsIContent::eHTML)) {
+      if (tag == nsHTMLAtoms::option)
+        SerializeOption(content, aParentIndex, aIndex, aRows);
+    }
     *aIndex += aRows.Count() - count;
   }
 }
@@ -1074,7 +1103,10 @@ nsOutlinerContentView::SerializeOption(nsIContent* aContent, PRInt32 aParentInde
   // This will happen before the OutlinerSelection is hooked up.  So, cache the selected
   // state in the row properties and update the selection when it is attached.
 
-  if (aContent->HasAttr(kNameSpaceID_None, nsLayoutAtoms::optionSelectedPseudo))
+  nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(aContent);
+  PRBool isSelected;
+  optEl->GetSelected(&isSelected);
+  if (isSelected)
     mUpdateSelection = PR_TRUE;
 }
 
diff --git a/layout/xul/base/src/outliner/src/nsOutlinerContentView.h b/layout/xul/base/src/outliner/src/nsOutlinerContentView.h
index 20fc263dcbf2..beaf67e8dda6 100644
--- a/layout/xul/base/src/outliner/src/nsOutlinerContentView.h
+++ b/layout/xul/base/src/outliner/src/nsOutlinerContentView.h
@@ -91,7 +91,8 @@ class nsOutlinerContentView : public nsIOutlinerView,
 
     NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                     nsIContent* aContent1,
-                                    nsIContent* aContent2);
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudo);
 
     NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                                 nsIContent*  aContent,
diff --git a/layout/xul/base/src/tree/src/nsTreeContentView.cpp b/layout/xul/base/src/tree/src/nsTreeContentView.cpp
index df7c4861f0c4..86ba4d04231a 100644
--- a/layout/xul/base/src/tree/src/nsTreeContentView.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeContentView.cpp
@@ -41,6 +41,7 @@
 #include "nsINameSpaceManager.h"
 #include "nsHTMLAtoms.h"
 #include "nsXULAtoms.h"
+#include "nsCSSAtoms.h"
 #include "nsLayoutAtoms.h"
 #include "nsIDOMDocument.h"
 #include "nsIBoxObject.h"
@@ -221,8 +222,13 @@ nsOutlinerContentView::SetSelection(nsIOutlinerSelection* aSelection)
     mSelection->SetSelectEventsSuppressed(PR_TRUE);
     for (PRInt32 i = 0; i < mRows.Count(); ++i) {
       Row* row = (Row*)mRows[i];
-      if (row->mContent->HasAttr(kNameSpaceID_None, nsLayoutAtoms::optionSelectedPseudo))
-        mSelection->ToggleSelect(i);
+      nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(row->mContent);
+      if (optEl) {
+        PRBool isSelected;
+        optEl->GetSelected(&isSelected);
+        if (isSelected)
+          mSelection->ToggleSelect(i);
+      }
     }
     mSelection->SetSelectEventsSuppressed(PR_FALSE);
   }
@@ -648,8 +654,22 @@ nsOutlinerContentView::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 nsOutlinerContentView::ContentStatesChanged(nsIDocument* aDocument,
                                            nsIContent* aContent1,
-                                           nsIContent* aContent2)
+                                           nsIContent* aContent2,
+                                           nsIAtom* aChangedPseudoClass)
 {
+  if (!aContent1 || !mSelection || !aContent1->IsContentOfType(nsIContent::eHTML) ||
+      aChangedPseudoClass != nsCSSAtoms::checkedPseudo)
+    return NS_OK;
+        
+  nsCOMPtr<nsIAtom> contentTag;
+  aContent1->GetTag(*getter_AddRefs(contentTag));   
+  if (contentTag == nsHTMLAtoms::option) {
+    // update the selected state for this node
+    PRInt32 index = FindContent(aContent1);
+    if (index >= 0)
+      mSelection->ToggleSelect(index);
+  }
+  
   return NS_OK;
 }
 
@@ -663,6 +683,10 @@ nsOutlinerContentView::AttributeChanged(nsIDocument *aDocument,
 {
   // First, get the element on which the attribute has changed
   // and then try to find content item in our array of rows.
+
+  if (!aContent->IsContentOfType(nsIContent::eXUL))
+    return NS_OK;
+
   nsCOMPtr<nsIAtom> tag;
   aContent->GetTag(*getter_AddRefs(tag));
 
@@ -734,16 +758,6 @@ nsOutlinerContentView::AttributeChanged(nsIDocument *aDocument,
       }
     }
   }
-  else if (tag == nsHTMLAtoms::option) {
-    if (aAttribute == nsLayoutAtoms::optionSelectedPseudo) {
-      PRInt32 index = FindContent(aContent);
-      if (index >= 0) {
-        NS_ASSERTION(mSelection, "Need to handle optionSelected change with no OutlinerSelection");
-        if (mSelection)
-          mSelection->ToggleSelect(index);
-      }
-    }
-  }
 
   return NS_OK;
 }
@@ -771,12 +785,17 @@ nsOutlinerContentView::ContentInserted(nsIDocument *aDocument,
   nsCOMPtr<nsIAtom> childTag;
   aChild->GetTag(*getter_AddRefs(childTag));
 
-  if ((childTag != nsXULAtoms::outlineritem) &&
-      (childTag != nsXULAtoms::outlinerseparator) &&
-      (childTag != nsHTMLAtoms::option) &&
-      (childTag != nsXULAtoms::outlinerchildren) &&
-      (childTag != nsXULAtoms::outlinerrow) &&
-      (childTag != nsXULAtoms::outlinercell))
+  if (aChild->IsContentOfType(nsIContent::eHTML)) {
+    if (childTag != nsHTMLAtoms::option)
+      return NS_OK;
+  } else if (aChild->IsContentOfType(nsIContent::eXUL)) {
+    if (childTag != nsXULAtoms::outlineritem &&
+        childTag != nsXULAtoms::outlinerseparator &&
+        childTag != nsXULAtoms::outlinerchildren &&
+        childTag != nsXULAtoms::outlinerrow &&
+        childTag != nsXULAtoms::outlinercell)
+      return NS_OK;
+  } else
     return NS_OK;
 
   // If we have a legal tag, go up to the outliner/select and make sure
@@ -786,7 +805,8 @@ nsOutlinerContentView::ContentInserted(nsIDocument *aDocument,
   
   while (element) {
     element->GetTag(*getter_AddRefs(parentTag));
-    if (parentTag == nsXULAtoms::outliner || parentTag == nsHTMLAtoms::select)
+    if ((element->IsContentOfType(nsIContent::eXUL) && parentTag == nsXULAtoms::outliner) ||
+        (element->IsContentOfType(nsIContent::eHTML) && parentTag == nsHTMLAtoms::select))
       if (element == mRoot) // this is for us, stop looking
         break;
       else // this is not for us, we can bail out
@@ -874,12 +894,17 @@ nsOutlinerContentView::ContentRemoved(nsIDocument *aDocument,
   nsCOMPtr<nsIAtom> tag;
   aChild->GetTag(*getter_AddRefs(tag));
 
-  if ((tag != nsXULAtoms::outlineritem) &&
-      (tag != nsXULAtoms::outlinerseparator) &&
-      (tag != nsHTMLAtoms::option) &&
-      (tag != nsXULAtoms::outlinerchildren) &&
-      (tag != nsXULAtoms::outlinerrow) &&
-      (tag != nsXULAtoms::outlinercell))
+  if (aChild->IsContentOfType(nsIContent::eHTML)) {
+    if (tag != nsHTMLAtoms::option)
+      return NS_OK;
+  } else if (aChild->IsContentOfType(nsIContent::eXUL)) {
+    if (tag != nsXULAtoms::outlineritem &&
+        tag != nsXULAtoms::outlinerseparator &&
+        tag != nsXULAtoms::outlinerchildren &&
+        tag != nsXULAtoms::outlinerrow &&
+        tag != nsXULAtoms::outlinercell)
+      return NS_OK;
+  } else
     return NS_OK;
 
   // If we have a legal tag, go up to the outliner/select and make sure
@@ -889,7 +914,8 @@ nsOutlinerContentView::ContentRemoved(nsIDocument *aDocument,
   
   while (element) {
     element->GetTag(*getter_AddRefs(parentTag));
-    if (parentTag == nsXULAtoms::outliner || parentTag == nsHTMLAtoms::select)
+    if ((element->IsContentOfType(nsIContent::eXUL) && parentTag == nsXULAtoms::outliner) || 
+        (element->IsContentOfType(nsIContent::eHTML) && parentTag == nsHTMLAtoms::select))
       if (element == mRoot) // this is for us, stop looking
         break;
       else // this is not for us, we can bail out
@@ -1010,12 +1036,15 @@ nsOutlinerContentView::Serialize(nsIContent* aContent, PRInt32 aParentIndex, PRI
     nsCOMPtr<nsIAtom> tag;
     content->GetTag(*getter_AddRefs(tag));
     PRInt32 count = aRows.Count();
-    if (tag == nsXULAtoms::outlineritem)
-      SerializeItem(content, aParentIndex, aIndex, aRows);
-    else if (tag == nsXULAtoms::outlinerseparator)
-      SerializeSeparator(content, aParentIndex, aIndex, aRows);
-    else if (tag == nsHTMLAtoms::option)
-      SerializeOption(content, aParentIndex, aIndex, aRows);
+    if (content->IsContentOfType(nsIContent::eXUL)) {
+      if (tag == nsXULAtoms::outlineritem)
+        SerializeItem(content, aParentIndex, aIndex, aRows);
+      else if (tag == nsXULAtoms::outlinerseparator)
+        SerializeSeparator(content, aParentIndex, aIndex, aRows);
+    } else if (content->IsContentOfType(nsIContent::eHTML)) {
+      if (tag == nsHTMLAtoms::option)
+        SerializeOption(content, aParentIndex, aIndex, aRows);
+    }
     *aIndex += aRows.Count() - count;
   }
 }
@@ -1074,7 +1103,10 @@ nsOutlinerContentView::SerializeOption(nsIContent* aContent, PRInt32 aParentInde
   // This will happen before the OutlinerSelection is hooked up.  So, cache the selected
   // state in the row properties and update the selection when it is attached.
 
-  if (aContent->HasAttr(kNameSpaceID_None, nsLayoutAtoms::optionSelectedPseudo))
+  nsCOMPtr<nsIDOMHTMLOptionElement> optEl = do_QueryInterface(aContent);
+  PRBool isSelected;
+  optEl->GetSelected(&isSelected);
+  if (isSelected)
     mUpdateSelection = PR_TRUE;
 }
 
diff --git a/layout/xul/base/src/tree/src/nsTreeContentView.h b/layout/xul/base/src/tree/src/nsTreeContentView.h
index 20fc263dcbf2..beaf67e8dda6 100644
--- a/layout/xul/base/src/tree/src/nsTreeContentView.h
+++ b/layout/xul/base/src/tree/src/nsTreeContentView.h
@@ -91,7 +91,8 @@ class nsOutlinerContentView : public nsIOutlinerView,
 
     NS_IMETHOD ContentStatesChanged(nsIDocument* aDocument,
                                     nsIContent* aContent1,
-                                    nsIContent* aContent2);
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudo);
 
     NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                                 nsIContent*  aContent,
diff --git a/webshell/tests/viewer/samples/aform.css b/webshell/tests/viewer/samples/aform.css
index bcb2329b8799..72fee109c691 100644
--- a/webshell/tests/viewer/samples/aform.css
+++ b/webshell/tests/viewer/samples/aform.css
@@ -47,17 +47,17 @@ select {
   border:2px inset rgb(192, 192, 192);
 }
 
-select[size] option[_moz-option-selected] {
+select[size] option:checked {
   background-color:rgb(0, 0, 128);
   color: white;
 }
 
-select option[_moz-option-selected] {
+select option:checked {
   background-color:rgb(0, 0, 128);
   color: white;
 }
 
-select[size="1"] option[_moz-option-selected] {
+select[size="1"] option:checked {
   background-color:rgb(0, 0, 128);
   color: white;
 }
diff --git a/webshell/tests/viewer/samples/bform.css b/webshell/tests/viewer/samples/bform.css
index 31516f8ec8e6..0f15c95fba27 100644
--- a/webshell/tests/viewer/samples/bform.css
+++ b/webshell/tests/viewer/samples/bform.css
@@ -37,7 +37,7 @@ option {
  padding-left:10px;
 }
 
-option[_moz-option-selected] {
+option:checked {
   color:black;
   background-color:rgb(255, 221, 255);
   padding-left:10px;
diff --git a/webshell/tests/viewer/samples/demoform.css b/webshell/tests/viewer/samples/demoform.css
index 8a6d036ad9cc..9dd90237df62 100644
--- a/webshell/tests/viewer/samples/demoform.css
+++ b/webshell/tests/viewer/samples/demoform.css
@@ -59,7 +59,7 @@ option {
  background-color:green;
 }
 
-option[_moz-option-selected] {
+option:checked {
   color:red;
   background-color:yellow;
 }
diff --git a/webshell/tests/viewer/samples/mozform.css b/webshell/tests/viewer/samples/mozform.css
index ee1ac5f3a03e..67c4325c8791 100644
--- a/webshell/tests/viewer/samples/mozform.css
+++ b/webshell/tests/viewer/samples/mozform.css
@@ -215,18 +215,18 @@ option {
 }
 
 /* Combobox item style */
-select option[_moz-option-selected] {
+select option:checked {
  color:black;
  background-color:white; 
 }
 
 /* List box item selected style */
-select[size] option[_moz-option-selected] {
+select[size] option:checked {
  color:white;
  background-color:rgb(51,51,102); 
 }
 
-select[size="1"] option[_moz-option-selected] {
+select[size="1"] option:checked {
   color:black;
   background-color:white;
 }
@@ -253,4 +253,4 @@ textarea {
   border: 2px inset #c0c0c0;
   background-color:white;
   color:black;
-}
\ No newline at end of file
+}
diff --git a/widget/src/cocoa/nsMenuBarX.cpp b/widget/src/cocoa/nsMenuBarX.cpp
index b8eb158679c0..e9dd69c6a76c 100644
--- a/widget/src/cocoa/nsMenuBarX.cpp
+++ b/widget/src/cocoa/nsMenuBarX.cpp
@@ -770,7 +770,8 @@ nsMenuBarX::ContentChanged( nsIDocument * aDocument, nsIContent * aContent, nsIS
 }
 
 NS_IMETHODIMP
-nsMenuBarX::ContentStatesChanged( nsIDocument * aDocument, nsIContent  * aContent1, nsIContent  * aContent2)
+nsMenuBarX::ContentStatesChanged( nsIDocument * aDocument, nsIContent  * aContent1,
+                                  nsIContent  * aContent2, nsIAtom * aChangedPseudoClass)
 {
   return NS_OK;
 }
diff --git a/widget/src/cocoa/nsMenuBarX.h b/widget/src/cocoa/nsMenuBarX.h
index b52b31220834..c2c323573f5d 100644
--- a/widget/src/cocoa/nsMenuBarX.h
+++ b/widget/src/cocoa/nsMenuBarX.h
@@ -112,7 +112,8 @@ public:
                               nsISupports* aSubContent);
     NS_IMETHOD ContentStatesChanged(nsIDocument *aDocument,
                                     nsIContent* aContent1,
-                                    nsIContent* aContent2);
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudoClass);
     NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                                 nsIContent*  aContent,
                                 PRInt32      aNameSpaceID,
diff --git a/widget/src/mac/nsMenuBar.cpp b/widget/src/mac/nsMenuBar.cpp
index 8f5c021a60b7..ccdf057f5caf 100644
--- a/widget/src/mac/nsMenuBar.cpp
+++ b/widget/src/mac/nsMenuBar.cpp
@@ -664,7 +664,8 @@ nsMenuBar::ContentChanged( nsIDocument * aDocument, nsIContent * aContent, nsISu
 }
 
 NS_IMETHODIMP
-nsMenuBar::ContentStatesChanged( nsIDocument * aDocument, nsIContent  * aContent1, nsIContent  * aContent2)
+nsMenuBar::ContentStatesChanged( nsIDocument * aDocument, nsIContent  * aContent1,
+                                 nsIContent  * aContent2, nsIAtom * aChangedPseudoClass)
 {
   return NS_OK;
 }
diff --git a/widget/src/mac/nsMenuBar.h b/widget/src/mac/nsMenuBar.h
index 7e438dee0623..641596fc7d0e 100644
--- a/widget/src/mac/nsMenuBar.h
+++ b/widget/src/mac/nsMenuBar.h
@@ -115,7 +115,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIDocument *aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,
diff --git a/widget/src/mac/nsMenuBarX.cpp b/widget/src/mac/nsMenuBarX.cpp
index 5a0dba436595..28a32f1886c7 100644
--- a/widget/src/mac/nsMenuBarX.cpp
+++ b/widget/src/mac/nsMenuBarX.cpp
@@ -760,7 +760,8 @@ nsMenuBarX::ContentChanged( nsIDocument * aDocument, nsIContent * aContent, nsIS
 }
 
 NS_IMETHODIMP
-nsMenuBarX::ContentStatesChanged( nsIDocument * aDocument, nsIContent  * aContent1, nsIContent  * aContent2)
+nsMenuBarX::ContentStatesChanged( nsIDocument * aDocument, nsIContent  * aContent1,
+                                  nsIContent  * aContent2, nsIAtom * aChangedPseudoClass)
 {
   return NS_OK;
 }
diff --git a/widget/src/mac/nsMenuBarX.h b/widget/src/mac/nsMenuBarX.h
index 010faa0b4999..0a2d7fbe2171 100644
--- a/widget/src/mac/nsMenuBarX.h
+++ b/widget/src/mac/nsMenuBarX.h
@@ -114,7 +114,8 @@ public:
                               nsISupports* aSubContent);
     NS_IMETHOD ContentStatesChanged(nsIDocument *aDocument,
                                     nsIContent* aContent1,
-                                    nsIContent* aContent2);
+                                    nsIContent* aContent2,
+                                    nsIAtom* aChangedPseudoClass);
     NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                                 nsIContent*  aContent,
                                 PRInt32      aNameSpaceID,
diff --git a/xpfe/appshell/src/nsWebShellWindow.cpp b/xpfe/appshell/src/nsWebShellWindow.cpp
index 6ad1ee5ddf81..22b50d1b6f9c 100644
--- a/xpfe/appshell/src/nsWebShellWindow.cpp
+++ b/xpfe/appshell/src/nsWebShellWindow.cpp
@@ -1550,7 +1550,8 @@ nsWebShellWindow::ContentChanged(nsIDocument *aDocument,
 NS_IMETHODIMP
 nsWebShellWindow::ContentStatesChanged(nsIDocument *aDocument,
                                        nsIContent* aContent1,
-                                       nsIContent* aContent2)
+                                       nsIContent* aContent2,
+                                       nsIAtom* aChangedPseudoClass)
 {
   return NS_OK;
 }
diff --git a/xpfe/appshell/src/nsWebShellWindow.h b/xpfe/appshell/src/nsWebShellWindow.h
index 34222a4cb72a..f3e003e86fca 100644
--- a/xpfe/appshell/src/nsWebShellWindow.h
+++ b/xpfe/appshell/src/nsWebShellWindow.h
@@ -124,7 +124,8 @@ public:
                             nsISupports* aSubContent);
   NS_IMETHOD ContentStatesChanged(nsIDocument *aDocument,
                                   nsIContent* aContent1,
-                                  nsIContent* aContent2);
+                                  nsIContent* aContent2,
+                                  nsIAtom* aChangedPseudoClass);
   NS_IMETHOD AttributeChanged(nsIDocument *aDocument,
                               nsIContent*  aContent,
                               PRInt32      aNameSpaceID,