--- a/widget/BasicEvents.h
+++ b/widget/BasicEvents.h
@@ -545,16 +545,37 @@ public:
   }
 
   WidgetEvent(const WidgetEvent& aOther)
     : WidgetEventTime()
   {
     MOZ_COUNT_CTOR(WidgetEvent);
     *this = aOther;
   }
+  WidgetEvent& operator=(const WidgetEvent& aOther) = default;
+
+  WidgetEvent(WidgetEvent&& aOther)
+    : WidgetEventTime(Move(aOther))
+    , mClass(aOther.mClass)
+    , mMessage(aOther.mMessage)
+    , mRefPoint(Move(aOther.mRefPoint))
+    , mLastRefPoint(Move(aOther.mLastRefPoint))
+    , mFocusSequenceNumber(aOther.mFocusSequenceNumber)
+    , mFlags(Move(aOther.mFlags))
+    , mSpecifiedEventType(Move(aOther.mSpecifiedEventType))
+    , mSpecifiedEventTypeString(Move(aOther.mSpecifiedEventTypeString))
+    , mTarget(Move(aOther.mTarget))
+    , mCurrentTarget(Move(aOther.mCurrentTarget))
+    , mOriginalTarget(Move(aOther.mOriginalTarget))
+    , mRelatedTarget(Move(aOther.mRelatedTarget))
+    , mPath(Move(aOther.mPath))
+  {
+    MOZ_COUNT_CTOR(WidgetEvent);
+  }
+  WidgetEvent& operator=(WidgetEvent&& aOther) = default;
 
   virtual WidgetEvent* Duplicate() const
   {
     MOZ_ASSERT(mClass == eBasicEventClass,
                "Duplicate() must be overridden by sub class");
     WidgetEvent* result = new WidgetEvent(false, mMessage);
     result->AssignEventData(*this, true);
     result->mFlags = mFlags;