--- a/editor/libeditor/HTMLEditor.h
+++ b/editor/libeditor/HTMLEditor.h
@@ -125,18 +125,16 @@ public:
                      bool aSuppressTransaction) override;
   virtual nsresult SetAttributeOrEquivalent(Element* aElement,
                                             nsAtom* aAttribute,
                                             const nsAString& aValue,
                                             bool aSuppressTransaction) override;
   using EditorBase::RemoveAttributeOrEquivalent;
   using EditorBase::SetAttributeOrEquivalent;
 
-  nsresult MouseMove(nsIDOMMouseEvent* aMouseEvent);
-
   // nsStubMutationObserver overrides
   NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
   NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
   NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
 
   // nsIHTMLEditor methods
   NS_DECL_NSIHTMLEDITOR
 
@@ -439,16 +437,40 @@ public:
   {
     return mDefaultParagraphSeparator;
   }
   void SetDefaultParagraphSeparator(ParagraphSeparator aSep)
   {
     mDefaultParagraphSeparator = aSep;
   }
 
+  /**
+   * event callback when a mouse button is pressed
+   * @param aX      [IN] horizontal position of the pointer
+   * @param aY      [IN] vertical position of the pointer
+   * @param aTarget [IN] the element triggering the event
+   * @param aMouseEvent [IN] the event
+   */
+  nsresult MouseDown(int32_t aX, int32_t aY, nsIDOMElement* aTarget,
+                     nsIDOMEvent* aMouseEvent);
+
+  /**
+   * event callback when a mouse button is released
+   * @param aX      [IN] horizontal position of the pointer
+   * @param aY      [IN] vertical position of the pointer
+   * @param aTarget [IN] the element triggering the event
+   */
+  nsresult MouseUp(int32_t aX, int32_t aY, nsIDOMElement* aTarget);
+
+  /**
+   * event callback when the mouse pointer is moved
+   * @param aMouseEvent [IN] the event
+   */
+  nsresult MouseMove(nsIDOMMouseEvent* aMouseEvent);
+
 protected:
   class BlobReader final : public nsIEditorBlobListener
   {
   public:
     BlobReader(dom::BlobImpl* aBlob, HTMLEditor* aHTMLEditor,
                bool aIsSafe, nsIDOMDocument* aSourceDoc,
                nsIDOMNode* aDestinationNode, int32_t aDestOffset,
                bool aDoDeleteSelection);

--- a/editor/libeditor/HTMLEditorObjectResizer.cpp
+++ b/editor/libeditor/HTMLEditorObjectResizer.cpp
@@ -543,17 +543,17 @@ HTMLEditor::StartResizing(nsIDOMElement*
     result = target->AddEventListener(NS_LITERAL_STRING("mousemove"),
                                       mMouseMotionListenerP, true);
     NS_ASSERTION(NS_SUCCEEDED(result),
                  "failed to register mouse motion listener");
   }
   return result;
 }
 
-NS_IMETHODIMP
+nsresult
 HTMLEditor::MouseDown(int32_t aClientX,
                       int32_t aClientY,
                       nsIDOMElement* aTarget,
                       nsIDOMEvent* aEvent)
 {
   bool anonElement = false;
   if (aTarget && NS_SUCCEEDED(aTarget->HasAttribute(NS_LITERAL_STRING("_moz_anonclass"), &anonElement)))
     // we caught a click on an anonymous element
@@ -575,17 +575,17 @@ HTMLEditor::MouseDown(int32_t aClientX,
         mOriginalX = aClientX;
         mOriginalY = aClientY;
         return GrabberClicked();
       }
     }
   return NS_OK;
 }
 
-NS_IMETHODIMP
+nsresult
 HTMLEditor::MouseUp(int32_t aClientX,
                     int32_t aClientY,
                     nsIDOMElement* aTarget)
 {
   if (mIsResizing) {
     // we are resizing and release the mouse button, so let's
     // end the resizing process
     mIsResizing = false;
@@ -800,26 +800,16 @@ HTMLEditor::GetNewResizingHeight(int32_t
                                  int32_t aY)
 {
   int32_t resized = mResizedObjectHeight +
                      GetNewResizingIncrement(aX, aY, kHeight) *
                          mHeightIncrementFactor;
   return std::max(resized, 1);
 }
 
-NS_IMETHODIMP
-HTMLEditor::MouseMove(nsIDOMEvent* aMouseEvent)
-{
-  nsCOMPtr<nsIDOMMouseEvent> mouseEvent = do_QueryInterface(aMouseEvent);
-  if (NS_WARN_IF(!mouseEvent)) {
-    return NS_OK;
-  }
-  return MouseMove(mouseEvent);
-}
-
 nsresult
 HTMLEditor::MouseMove(nsIDOMMouseEvent* aMouseEvent)
 {
   MOZ_ASSERT(aMouseEvent);
 
   if (mIsResizing) {
     // we are resizing and the mouse pointer's position has changed
     // we have to resdisplay the shadow

--- a/editor/nsIHTMLObjectResizer.idl
+++ b/editor/nsIHTMLObjectResizer.idl
@@ -42,35 +42,10 @@ interface nsIHTMLObjectResizer : nsISupp
    * Hide resizers if they are visible
    */
   void hideResizers();
 
   /**
    * Refresh visible resizers
    */
   void refreshResizers();
-
-  /**
-   * event callback when a mouse button is pressed
-   * @param aX      [IN] horizontal position of the pointer
-   * @param aY      [IN] vertical position of the pointer
-   * @param aTarget [IN] the element triggering the event
-   * @param aMouseEvent [IN] the event
-   */
-  void mouseDown(in long aX, in long aY,
-                 in nsIDOMElement aTarget, in nsIDOMEvent aMouseEvent);
-
-  /**
-   * event callback when a mouse button is released
-   * @param aX      [IN] horizontal position of the pointer
-   * @param aY      [IN] vertical position of the pointer
-   * @param aTarget [IN] the element triggering the event
-   */
-  void mouseUp(in long aX, in long aY,
-               in nsIDOMElement aTarget);
-
-  /**
-   * event callback when the mouse pointer is moved
-   * @param aMouseEvent [IN] the event
-   */
-  void mouseMove(in nsIDOMEvent aMouseEvent);
 };