diff --git a/content/base/public/nsContentUtils.h b/content/base/public/nsContentUtils.h
index d416c22bd32b..a09b92872dbe 100644
--- a/content/base/public/nsContentUtils.h
+++ b/content/base/public/nsContentUtils.h
@@ -1407,9 +1407,9 @@ public:
   static already_AddRefed<nsIDragSession> GetDragSession();
 
   /*
-   * Initialize and set the dataTransfer field of an nsDragEvent.
+   * Initialize and set the dataTransfer field of an WidgetDragEvent.
    */
-  static nsresult SetDataTransferInEvent(nsDragEvent* aDragEvent);
+  static nsresult SetDataTransferInEvent(mozilla::WidgetDragEvent* aDragEvent);
 
   // filters the drag and drop action to fit within the effects allowed and
   // returns it.
@@ -1420,7 +1420,7 @@ public:
    * an ancestor of the document for the source of the drag.
    */
   static bool CheckForSubFrameDrop(nsIDragSession* aDragSession,
-                                   nsDragEvent* aDropEvent);
+                                   mozilla::WidgetDragEvent* aDropEvent);
 
   /**
    * Return true if aURI is a local file URI (i.e. file://).
diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index 8e4c87fb678a..c57d8316dab6 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -4979,7 +4979,7 @@ nsContentUtils::GetDragSession()
 
 /* static */
 nsresult
-nsContentUtils::SetDataTransferInEvent(nsDragEvent* aDragEvent)
+nsContentUtils::SetDataTransferInEvent(WidgetDragEvent* aDragEvent)
 {
   if (aDragEvent->dataTransfer || !aDragEvent->mFlags.mIsTrusted)
     return NS_OK;
@@ -5081,7 +5081,8 @@ nsContentUtils::FilterDropEffect(uint32_t aAction, uint32_t aEffectAllowed)
 
 /* static */
 bool
-nsContentUtils::CheckForSubFrameDrop(nsIDragSession* aDragSession, nsDragEvent* aDropEvent)
+nsContentUtils::CheckForSubFrameDrop(nsIDragSession* aDragSession,
+                                     WidgetDragEvent* aDropEvent)
 {
   nsCOMPtr<nsIContent> target = do_QueryInterface(aDropEvent->originalTarget);
   if (!target) {
diff --git a/content/events/src/nsDOMDragEvent.cpp b/content/events/src/nsDOMDragEvent.cpp
index 97c2a13880cd..e28918378351 100644
--- a/content/events/src/nsDOMDragEvent.cpp
+++ b/content/events/src/nsDOMDragEvent.cpp
@@ -15,7 +15,7 @@ nsDOMDragEvent::nsDOMDragEvent(mozilla::dom::EventTarget* aOwner,
                                nsPresContext* aPresContext,
                                WidgetInputEvent* aEvent)
   : nsDOMMouseEvent(aOwner, aPresContext, aEvent ? aEvent :
-                    new nsDragEvent(false, 0, nullptr))
+                    new WidgetDragEvent(false, 0, nullptr))
 {
   if (aEvent) {
     mEventIsInternal = false;
@@ -32,7 +32,7 @@ nsDOMDragEvent::~nsDOMDragEvent()
 {
   if (mEventIsInternal) {
     if (mEvent->eventStructType == NS_DRAG_EVENT)
-      delete static_cast<nsDragEvent*>(mEvent);
+      delete static_cast<WidgetDragEvent*>(mEvent);
     mEvent = nullptr;
   }
 }
@@ -62,7 +62,7 @@ nsDOMDragEvent::InitDragEvent(const nsAString & aType,
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (mEventIsInternal && mEvent) {
-    nsDragEvent* dragEvent = static_cast<nsDragEvent*>(mEvent);
+    WidgetDragEvent* dragEvent = static_cast<WidgetDragEvent*>(mEvent);
     dragEvent->dataTransfer = aDataTransfer;
   }
 
@@ -88,7 +88,7 @@ nsDOMDragEvent::GetDataTransfer()
     return nullptr;
   }
 
-  nsDragEvent* dragEvent = static_cast<nsDragEvent*>(mEvent);
+  WidgetDragEvent* dragEvent = static_cast<WidgetDragEvent*>(mEvent);
   // for synthetic events, just use the supplied data transfer object even if null
   if (!mEventIsInternal) {
     nsresult rv = nsContentUtils::SetDataTransferInEvent(dragEvent);
@@ -101,7 +101,7 @@ nsDOMDragEvent::GetDataTransfer()
 nsresult NS_NewDOMDragEvent(nsIDOMEvent** aInstancePtrResult,
                             mozilla::dom::EventTarget* aOwner,
                             nsPresContext* aPresContext,
-                            nsDragEvent *aEvent) 
+                            WidgetDragEvent* aEvent) 
 {
   nsDOMDragEvent* event = new nsDOMDragEvent(aOwner, aPresContext, aEvent);
   return CallQueryInterface(event, aInstancePtrResult);
diff --git a/content/events/src/nsDOMDragEvent.h b/content/events/src/nsDOMDragEvent.h
index ac9abe4a1442..5ace30c64398 100644
--- a/content/events/src/nsDOMDragEvent.h
+++ b/content/events/src/nsDOMDragEvent.h
@@ -55,6 +55,6 @@ public:
 nsresult NS_NewDOMDragEvent(nsIDOMEvent** aInstancePtrResult,
                             mozilla::dom::EventTarget* aOwner,
                             nsPresContext* aPresContext,
-                            nsDragEvent* aEvent);
+                            mozilla::WidgetDragEvent* aEvent);
 
 #endif // nsDOMDragEvent_h__
diff --git a/content/events/src/nsDOMEvent.cpp b/content/events/src/nsDOMEvent.cpp
index 96a29b7e18c0..ccd433993777 100644
--- a/content/events/src/nsDOMEvent.cpp
+++ b/content/events/src/nsDOMEvent.cpp
@@ -147,7 +147,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDOMEvent)
           nullptr;
         break;
       case NS_DRAG_EVENT:
-        static_cast<nsDragEvent*>(tmp->mEvent)->dataTransfer = nullptr;
+        static_cast<WidgetDragEvent*>(tmp->mEvent)->dataTransfer = nullptr;
         static_cast<WidgetMouseEventBase*>(tmp->mEvent)->relatedTarget =
           nullptr;
         break;
@@ -189,7 +189,7 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsDOMEvent)
       case NS_DRAG_EVENT:
         NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mEvent->dataTransfer");
         cb.NoteXPCOMChild(
-          static_cast<nsDragEvent*>(tmp->mEvent)->dataTransfer);
+          static_cast<WidgetDragEvent*>(tmp->mEvent)->dataTransfer);
         NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mEvent->relatedTarget");
         cb.NoteXPCOMChild(
           static_cast<WidgetMouseEventBase*>(tmp->mEvent)->relatedTarget);
@@ -559,9 +559,8 @@ nsDOMEvent::DuplicatePrivateData()
     }
     case NS_DRAG_EVENT:
     {
-      nsDragEvent* oldDragEvent = static_cast<nsDragEvent*>(mEvent);
-      nsDragEvent* dragEvent =
-        new nsDragEvent(false, msg, nullptr);
+      WidgetDragEvent* oldDragEvent = static_cast<WidgetDragEvent*>(mEvent);
+      WidgetDragEvent* dragEvent = new WidgetDragEvent(false, msg, nullptr);
       dragEvent->AssignDragEventData(*oldDragEvent, true);
       newEvent = dragEvent;
       break;
diff --git a/content/events/src/nsEventDispatcher.cpp b/content/events/src/nsEventDispatcher.cpp
index f26478059395..ca50c8b2b9ff 100644
--- a/content/events/src/nsEventDispatcher.cpp
+++ b/content/events/src/nsEventDispatcher.cpp
@@ -722,7 +722,7 @@ nsEventDispatcher::CreateEvent(mozilla::dom::EventTarget* aOwner,
                                  static_cast<WheelEvent*>(aEvent));
     case NS_DRAG_EVENT:
       return NS_NewDOMDragEvent(aDOMEvent, aOwner, aPresContext,
-                                 static_cast<nsDragEvent*>(aEvent));
+                                static_cast<WidgetDragEvent*>(aEvent));
     case NS_TEXT_EVENT:
       return NS_NewDOMTextEvent(aDOMEvent, aOwner, aPresContext,
                                 static_cast<WidgetTextEvent*>(aEvent));
diff --git a/content/events/src/nsEventStateManager.cpp b/content/events/src/nsEventStateManager.cpp
index 96cdb621c954..51f363960f3f 100644
--- a/content/events/src/nsEventStateManager.cpp
+++ b/content/events/src/nsEventStateManager.cpp
@@ -1928,12 +1928,12 @@ nsEventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
       nsCOMPtr<nsIWidget> widget = mCurrentTarget->GetNearestWidget();
 
       // get the widget from the target frame
-      nsDragEvent startEvent(aEvent->mFlags.mIsTrusted,
-                             NS_DRAGDROP_START, widget);
+      WidgetDragEvent startEvent(aEvent->mFlags.mIsTrusted,
+                                 NS_DRAGDROP_START, widget);
       FillInEventFromGestureDown(&startEvent);
 
-      nsDragEvent gestureEvent(aEvent->mFlags.mIsTrusted,
-                               NS_DRAGDROP_GESTURE, widget);
+      WidgetDragEvent gestureEvent(aEvent->mFlags.mIsTrusted,
+                                   NS_DRAGDROP_GESTURE, widget);
       FillInEventFromGestureDown(&gestureEvent);
 
       startEvent.dataTransfer = gestureEvent.dataTransfer = dataTransfer;
@@ -1961,7 +1961,7 @@ nsEventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
       nsEventDispatcher::Dispatch(targetContent, aPresContext, &startEvent, nullptr,
                                   &status);
 
-      nsDragEvent* event = &startEvent;
+      WidgetDragEvent* event = &startEvent;
       if (status != nsEventStatus_eConsumeNoDefault) {
         status = nsEventStatus_eIgnore;
         nsEventDispatcher::Dispatch(targetContent, aPresContext, &gestureEvent, nullptr,
@@ -2086,7 +2086,7 @@ nsEventStateManager::DetermineDragTarget(nsPresContext* aPresContext,
 
 bool
 nsEventStateManager::DoDefaultDragStart(nsPresContext* aPresContext,
-                                        nsDragEvent* aDragEvent,
+                                        WidgetDragEvent* aDragEvent,
                                         nsDOMDataTransfer* aDataTransfer,
                                         nsIContent* aDragTarget,
                                         nsISelection* aSelection)
@@ -3253,7 +3253,7 @@ nsEventStateManager::PostHandleEvent(nsPresContext* aPresContext,
       nsCOMPtr<nsIDOMDataTransfer> initialDataTransfer;
       dragSession->GetDataTransfer(getter_AddRefs(initialDataTransfer));
 
-      nsDragEvent *dragEvent = (nsDragEvent*)aEvent;
+      WidgetDragEvent *dragEvent = static_cast<WidgetDragEvent*>(aEvent);
 
       // collect any changes to moz cursor settings stored in the event's
       // data transfer.
@@ -3348,8 +3348,8 @@ nsEventStateManager::PostHandleEvent(nsPresContext* aPresContext,
                                            getter_AddRefs(targetContent));
 
         nsCOMPtr<nsIWidget> widget = mCurrentTarget->GetNearestWidget();
-        nsDragEvent event(aEvent->mFlags.mIsTrusted,
-                          NS_DRAGDROP_DRAGDROP, widget);
+        WidgetDragEvent event(aEvent->mFlags.mIsTrusted,
+                              NS_DRAGDROP_DRAGDROP, widget);
 
         nsMouseEvent* mouseEvent = static_cast<nsMouseEvent*>(aEvent);
         event.refPoint = mouseEvent->refPoint;
@@ -4275,7 +4275,7 @@ nsEventStateManager::FireDragEnterOrExit(nsPresContext* aPresContext,
                                          nsWeakFrame& aTargetFrame)
 {
   nsEventStatus status = nsEventStatus_eIgnore;
-  nsDragEvent event(aEvent->mFlags.mIsTrusted, aMsg, aEvent->widget);
+  WidgetDragEvent event(aEvent->mFlags.mIsTrusted, aMsg, aEvent->widget);
   event.refPoint = aEvent->refPoint;
   event.modifiers = ((nsMouseEvent*)aEvent)->modifiers;
   event.buttons = ((nsMouseEvent*)aEvent)->buttons;
@@ -4308,7 +4308,7 @@ nsEventStateManager::FireDragEnterOrExit(nsPresContext* aPresContext,
 }
 
 void
-nsEventStateManager::UpdateDragDataTransfer(nsDragEvent* dragEvent)
+nsEventStateManager::UpdateDragDataTransfer(WidgetDragEvent* dragEvent)
 {
   NS_ASSERTION(dragEvent, "drag event is null in UpdateDragDataTransfer!");
   if (!dragEvent->dataTransfer)
diff --git a/content/events/src/nsEventStateManager.h b/content/events/src/nsEventStateManager.h
index 7f0941ad3db2..f65e4db01c36 100644
--- a/content/events/src/nsEventStateManager.h
+++ b/content/events/src/nsEventStateManager.h
@@ -292,7 +292,7 @@ protected:
    * Update the initial drag session data transfer with any changes that occur
    * on cloned data transfer objects used for events.
    */
-  void UpdateDragDataTransfer(nsDragEvent* dragEvent);
+  void UpdateDragDataTransfer(mozilla::WidgetDragEvent* dragEvent);
 
   nsresult SetClickCount(nsPresContext* aPresContext, nsMouseEvent *aEvent, nsEventStatus* aStatus);
   nsresult CheckForAndDispatchClick(nsPresContext* aPresContext, nsMouseEvent *aEvent, nsEventStatus* aStatus);
@@ -691,10 +691,10 @@ protected:
    * aSelection - the selection to be dragged
    */
   bool DoDefaultDragStart(nsPresContext* aPresContext,
-                            nsDragEvent* aDragEvent,
-                            nsDOMDataTransfer* aDataTransfer,
-                            nsIContent* aDragTarget,
-                            nsISelection* aSelection);
+                          mozilla::WidgetDragEvent* aDragEvent,
+                          nsDOMDataTransfer* aDataTransfer,
+                          nsIContent* aDragTarget,
+                          nsISelection* aSelection);
 
   bool IsTrackingDragGesture ( ) const { return mGestureDownContent != nullptr; }
   /**
diff --git a/dom/interfaces/events/nsIDOMEvent.idl b/dom/interfaces/events/nsIDOMEvent.idl
index adf84e550113..a585fc2d4fe2 100644
--- a/dom/interfaces/events/nsIDOMEvent.idl
+++ b/dom/interfaces/events/nsIDOMEvent.idl
@@ -262,7 +262,7 @@ nsresult
 NS_NewDOMDragEvent(nsIDOMEvent** aInstancePtrResult,
                    mozilla::dom::EventTarget* aOwner,
                    nsPresContext* aPresContext,
-                   nsDragEvent* aEvent);
+                   mozilla::WidgetDragEvent* aEvent);
 nsresult
 NS_NewDOMClipboardEvent(nsIDOMEvent** aInstancePtrResult,
                         mozilla::dom::EventTarget* aOwner,
diff --git a/editor/libeditor/text/nsPlaintextDataTransfer.cpp b/editor/libeditor/text/nsPlaintextDataTransfer.cpp
index 2269b4b27dfb..8bc66218ae1e 100644
--- a/editor/libeditor/text/nsPlaintextDataTransfer.cpp
+++ b/editor/libeditor/text/nsPlaintextDataTransfer.cpp
@@ -182,7 +182,8 @@ nsresult nsPlaintextEditor::InsertFromDrop(nsIDOMEvent* aDropEvent)
     NS_ENSURE_TRUE(sourceNode, NS_ERROR_FAILURE);
   }
 
-  nsDragEvent* dragEventInternal = static_cast<nsDragEvent *>(aDropEvent->GetInternalNSEvent());
+  WidgetDragEvent* dragEventInternal =
+    static_cast<WidgetDragEvent*>(aDropEvent->GetInternalNSEvent());
   if (nsContentUtils::CheckForSubFrameDrop(dragSession, dragEventInternal)) {
     // Don't allow drags from subframe documents with different origins than
     // the drop destination.
diff --git a/layout/xul/tree/nsTreeBodyFrame.cpp b/layout/xul/tree/nsTreeBodyFrame.cpp
index 46b8a4b73c4e..565c3c40673f 100644
--- a/layout/xul/tree/nsTreeBodyFrame.cpp
+++ b/layout/xul/tree/nsTreeBodyFrame.cpp
@@ -2554,7 +2554,7 @@ nsTreeBodyFrame::GetCursor(const nsPoint& aPoint,
 static uint32_t GetDropEffect(nsGUIEvent* aEvent)
 {
   NS_ASSERTION(aEvent->eventStructType == NS_DRAG_EVENT, "wrong event type");
-  nsDragEvent* dragEvent = static_cast<nsDragEvent *>(aEvent);
+  WidgetDragEvent* dragEvent = static_cast<WidgetDragEvent*>(aEvent);
   nsContentUtils::SetDataTransferInEvent(dragEvent);
 
   uint32_t action = 0;
@@ -2700,7 +2700,7 @@ nsTreeBodyFrame::HandleEvent(nsPresContext* aPresContext,
 
         // The dataTransfer was initialized by the call to GetDropEffect above.
         bool canDropAtNewLocation = false;
-        nsDragEvent* dragEvent = static_cast<nsDragEvent *>(aEvent);
+        WidgetDragEvent* dragEvent = static_cast<WidgetDragEvent*>(aEvent);
         mView->CanDrop(mSlots->mDropRow, mSlots->mDropOrient,
                        dragEvent->dataTransfer, &canDropAtNewLocation);
 
@@ -2732,7 +2732,7 @@ nsTreeBodyFrame::HandleEvent(nsPresContext* aPresContext,
     }
 
     NS_ASSERTION(aEvent->eventStructType == NS_DRAG_EVENT, "wrong event type");
-    nsDragEvent* dragEvent = static_cast<nsDragEvent*>(aEvent);
+    WidgetDragEvent* dragEvent = static_cast<WidgetDragEvent*>(aEvent);
     nsContentUtils::SetDataTransferInEvent(dragEvent);
 
     mView->Drop(mSlots->mDropRow, mSlots->mDropOrient, dragEvent->dataTransfer);
diff --git a/widget/EventForwards.h b/widget/EventForwards.h
index 2695ee850c60..db60b1197aa5 100644
--- a/widget/EventForwards.h
+++ b/widget/EventForwards.h
@@ -106,7 +106,6 @@ class InternalMutationEvent;
 typedef mozilla::WidgetEvent               nsEvent;
 typedef mozilla::WidgetGUIEvent            nsGUIEvent;
 typedef mozilla::WidgetMouseEvent          nsMouseEvent;
-typedef mozilla::WidgetDragEvent           nsDragEvent;
 typedef mozilla::WidgetMouseScrollEvent    nsMouseScrollEvent;
 
 namespace mozilla {
diff --git a/widget/MouseEvents.h b/widget/MouseEvents.h
index f5d5188f4557..1373027da5d5 100644
--- a/widget/MouseEvents.h
+++ b/widget/MouseEvents.h
@@ -425,7 +425,6 @@ typedef WidgetWheelEvent                WheelEvent;
 
 // TODO: Remove following typedefs
 typedef mozilla::WidgetMouseEvent       nsMouseEvent;
-typedef mozilla::WidgetDragEvent        nsDragEvent;
 typedef mozilla::WidgetMouseScrollEvent nsMouseScrollEvent;
 
 #endif // mozilla_MouseEvents_h__
diff --git a/widget/cocoa/nsChildView.mm b/widget/cocoa/nsChildView.mm
index cb439dc708fd..69bad8854a2e 100644
--- a/widget/cocoa/nsChildView.mm
+++ b/widget/cocoa/nsChildView.mm
@@ -5500,7 +5500,7 @@ static int32_t RoundUp(double aDouble)
   }
 
   // set up gecko event
-  nsDragEvent geckoEvent(true, aMessage, mGeckoChild);
+  WidgetDragEvent geckoEvent(true, aMessage, mGeckoChild);
   nsCocoaUtils::InitInputEvent(geckoEvent, [NSApp currentEvent]);
 
   // Use our own coordinates in the gecko event.
diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index 17c2161b576d..bf591dff706f 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -3258,7 +3258,7 @@ void
 nsWindow::DispatchDragEvent(uint32_t aMsg, const nsIntPoint& aRefPoint,
                             guint aTime)
 {
-    nsDragEvent event(true, aMsg, this);
+    WidgetDragEvent event(true, aMsg, this);
 
     if (aMsg == NS_DRAGDROP_OVER) {
         InitDragEvent(event);
@@ -5561,7 +5561,7 @@ theme_changed_cb (GtkSettings *settings, GParamSpec *pspec, nsWindow *data)
 // These are all of our drag and drop operations
 
 void
-nsWindow::InitDragEvent(nsDragEvent &aEvent)
+nsWindow::InitDragEvent(WidgetDragEvent &aEvent)
 {
     // set the keyboard modifiers
     guint modifierState = KeymapWrapper::GetCurrentModifierState();
diff --git a/widget/gtk/nsWindow.h b/widget/gtk/nsWindow.h
index 3371dd606604..1c3f2d9e2185 100644
--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -424,7 +424,7 @@ private:
     gchar*       mTransparencyBitmap;
  
     // all of our DND stuff
-    void   InitDragEvent         (nsDragEvent &aEvent);
+    void   InitDragEvent(mozilla::WidgetDragEvent& aEvent);
 
     float              mLastMotionPressure;
 
diff --git a/widget/os2/nsWindow.cpp b/widget/os2/nsWindow.cpp
index 29de290fb8a3..e675602efe40 100644
--- a/widget/os2/nsWindow.cpp
+++ b/widget/os2/nsWindow.cpp
@@ -3097,7 +3097,7 @@ bool nsWindow::DispatchCommandEvent(uint32_t aEventCommand)
 
 bool nsWindow::DispatchDragDropEvent(uint32_t aMsg)
 {
-  nsDragEvent event(true, aMsg, this);
+  WidgetDragEvent event(true, aMsg, this);
   InitEvent(event);
 
   event.InitBasicModifiers(isKeyDown(VK_CTRL),
diff --git a/widget/windows/nsNativeDragTarget.cpp b/widget/windows/nsNativeDragTarget.cpp
index d64cc271e312..b6e58f6ddf5b 100644
--- a/widget/windows/nsNativeDragTarget.cpp
+++ b/widget/windows/nsNativeDragTarget.cpp
@@ -19,6 +19,7 @@
 
 #include "mozilla/MouseEvents.h"
 
+using namespace mozilla;
 using namespace mozilla::widget;
 
 /* Define Class IDs */
@@ -155,7 +156,7 @@ void
 nsNativeDragTarget::DispatchDragDropEvent(uint32_t aEventType, POINTL aPT)
 {
   nsEventStatus status;
-  nsDragEvent event(true, aEventType, mWidget);
+  WidgetDragEvent event(true, aEventType, mWidget);
 
   nsWindow * win = static_cast<nsWindow *>(mWidget);
   win->InitEvent(event);
diff --git a/widget/xpwidgets/nsBaseDragService.cpp b/widget/xpwidgets/nsBaseDragService.cpp
index 885ad0fdb7eb..5f5bebcbf68e 100644
--- a/widget/xpwidgets/nsBaseDragService.cpp
+++ b/widget/xpwidgets/nsBaseDragService.cpp
@@ -370,7 +370,7 @@ nsBaseDragService::FireDragEventAtSource(uint32_t aMsg)
       nsCOMPtr<nsIPresShell> presShell = doc->GetShell();
       if (presShell) {
         nsEventStatus status = nsEventStatus_eIgnore;
-        nsDragEvent event(true, aMsg, nullptr);
+        WidgetDragEvent event(true, aMsg, nullptr);
         event.inputSource = mInputSource;
         if (aMsg == NS_DRAGDROP_END) {
           event.refPoint.x = mEndDragPoint.x;