--- a/editor/libeditor/html/nsHTMLAbsPosition.cpp
+++ b/editor/libeditor/html/nsHTMLAbsPosition.cpp
@@ -308,17 +308,19 @@ nsHTMLEditor::HideGrabber()
     mAbsolutelyPositionedObject->RemoveAttribute(NS_LITERAL_STRING("_moz_abspos"));
   if (NS_FAILED(res)) return res;
 
   mAbsolutelyPositionedObject = nsnull;
   NS_ENSURE_TRUE(mGrabber, NS_ERROR_NULL_POINTER);
 
   // get the presshell's document observer interface.
   nsCOMPtr<nsIPresShell> ps = do_QueryReferent(mPresShellWeak);
-  if (!ps) return NS_ERROR_NOT_INITIALIZED;
+  // We allow the pres shell to be null; when it is, we presume there
+  // are no document observers to notify, but we still want to
+  // UnbindFromTree.
 
   nsCOMPtr<nsIDOMNode> parentNode;
   res = mGrabber->GetParentNode(getter_AddRefs(parentNode));
   NS_ENSURE_SUCCESS(res, res);
 
   nsCOMPtr<nsIContent> parentContent = do_QueryInterface(parentNode);
   if (!parentContent) return NS_ERROR_NULL_POINTER;
 

--- a/editor/libeditor/html/nsHTMLInlineTableEditor.cpp
+++ b/editor/libeditor/html/nsHTMLInlineTableEditor.cpp
@@ -120,17 +120,19 @@ nsHTMLEditor::HideInlineTableEditingUI()
   RemoveMouseClickListener(mRemoveColumnButton);
   RemoveMouseClickListener(mAddColumnAfterButton);
   RemoveMouseClickListener(mAddRowBeforeButton);
   RemoveMouseClickListener(mRemoveRowButton);
   RemoveMouseClickListener(mAddRowAfterButton);
 
   // get the presshell's document observer interface.
   nsCOMPtr<nsIPresShell> ps = do_QueryReferent(mPresShellWeak);
-  if (!ps) return NS_ERROR_NOT_INITIALIZED;
+  // We allow the pres shell to be null; when it is, we presume there
+  // are no document observers to notify, but we still want to
+  // UnbindFromTree.
 
   // get the root content node.
 
   nsIDOMElement *bodyElement = GetRoot();
 
   nsCOMPtr<nsIContent> bodyContent( do_QueryInterface(bodyElement) );
   if (!bodyContent) return NS_ERROR_FAILURE;
 

--- a/editor/libeditor/html/nsHTMLObjectResizer.cpp
+++ b/editor/libeditor/html/nsHTMLObjectResizer.cpp
@@ -434,17 +434,19 @@ nsHTMLEditor::ShowResizersInner(nsIDOMEl
 NS_IMETHODIMP 
 nsHTMLEditor::HideResizers(void)
 {
   if (!mResizedObject)
     return NS_OK;
 
   // get the presshell's document observer interface.
   nsCOMPtr<nsIPresShell> ps = do_QueryReferent(mPresShellWeak);
-  if (!ps) return NS_ERROR_NOT_INITIALIZED;
+  // We allow the pres shell to be null; when it is, we presume there
+  // are no document observers to notify, but we still want to
+  // UnbindFromTree.
 
   nsresult res;
   nsCOMPtr<nsIDOMNode> parentNode;
   nsCOMPtr<nsIContent> parentContent;
 
   if (mTopLeftHandle) {
     res = mTopLeftHandle->GetParentNode(getter_AddRefs(parentNode));
     NS_ENSURE_SUCCESS(res, res);