--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -981,16 +981,18 @@ APZCTreeManager::ReceiveInputEvent(Input
     case MULTITOUCH_INPUT: {
       MultiTouchInput& touchInput = aEvent.AsMultiTouchInput();
       result = ProcessTouchInput(touchInput, aOutTargetGuid, aOutInputBlockId);
       break;
     } case MOUSE_INPUT: {
       MouseInput& mouseInput = aEvent.AsMouseInput();
       mouseInput.mHandledByAPZ = true;
 
+      mCurrentMousePosition = mouseInput.mOrigin;
+
       bool startsDrag = DragTracker::StartsDrag(mouseInput);
       if (startsDrag) {
         // If this is the start of a drag we need to unambiguously know if it's
         // going to land on a scrollbar or not. We can't apply an untransform
         // here without knowing that, so we need to ensure the untransform is
         // a no-op.
         FlushRepaintsToClearScreenToGeckoTransform();
       }
@@ -2473,16 +2475,22 @@ APZCTreeManager::GetApzcToGeckoTransform
     // The above value for result when parent == P matches the required output
     // as explained in the comment above this method. Note that any missing
     // terms are guaranteed to be identity transforms.
   }
 
   return ViewAs<ParentLayerToScreenMatrix4x4>(result);
 }
 
+ScreenPoint
+APZCTreeManager::GetCurrentMousePosition() const
+{
+  return mCurrentMousePosition;
+}
+
 already_AddRefed<AsyncPanZoomController>
 APZCTreeManager::GetMultitouchTarget(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const
 {
   MutexAutoLock lock(mTreeLock);
   RefPtr<AsyncPanZoomController> apzc;
   // For now, we only ever want to do pinching on the root-content APZC for
   // a given layers id.
   if (aApzc1 && aApzc2 && aApzc1->GetLayersId() == aApzc2->GetLayersId()) {

--- a/gfx/layers/apz/src/APZCTreeManager.h
+++ b/gfx/layers/apz/src/APZCTreeManager.h
@@ -480,16 +480,17 @@ public:
   RefPtr<HitTestingTreeNode> GetRootNode() const;
   already_AddRefed<AsyncPanZoomController> GetTargetAPZC(const ScreenPoint& aPoint,
                                                          HitTestResult* aOutHitResult,
                                                          RefPtr<HitTestingTreeNode>* aOutScrollbarNode = nullptr);
   already_AddRefed<AsyncPanZoomController> GetTargetAPZC(const uint64_t& aLayersId,
                                                          const FrameMetrics::ViewID& aScrollId);
   ScreenToParentLayerMatrix4x4 GetScreenToApzcTransform(const AsyncPanZoomController *aApzc) const;
   ParentLayerToScreenMatrix4x4 GetApzcToGeckoTransform(const AsyncPanZoomController *aApzc) const;
+  ScreenPoint GetCurrentMousePosition() const;
 
   /**
    * Process touch velocity.
    * Sometimes the touch move event will have a velocity even though no scrolling
    * is occurring such as when the toolbar is being hidden/shown in Fennec.
    * This function can be called to have the y axis' velocity queue updated.
    */
   void ProcessTouchVelocity(uint32_t aTimestampMs, float aSpeedY) override;
@@ -592,16 +593,19 @@ private:
   /* Sometimes we want to ignore all touches except one. In such cases, this
    * is set to the identifier of the touch we are not ignoring; in other cases,
    * this is set to -1.
    */
   int32_t mRetainedTouchIdentifier;
   /* Tracks the number of touch points we are tracking that are currently on
    * the screen. */
   TouchCounter mTouchCounter;
+  /* Stores the current mouse position in screen coordinates.
+   */
+  ScreenPoint mCurrentMousePosition;
   /* For logging the APZC tree for debugging (enabled by the apz.printtree
    * pref). */
   gfx::TreeLog mApzcTreeLog;
 
   class CheckerboardFlushObserver;
   friend class CheckerboardFlushObserver;
   RefPtr<CheckerboardFlushObserver> mFlushObserver;