--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -6838,13 +6838,94 @@ nsWindow::SynthesizeNativeMouseScrollEve
   }
 #endif
 
   gdk_event_put(&event);
 
   return NS_OK;
 }
 
+#if GTK_CHECK_VERSION(3,4,0)
+nsresult
+nsWindow::SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                     TouchPointerState aPointerState,
+                                     ScreenIntPoint aPointerScreenPoint,
+                                     double aPointerPressure,
+                                     uint32_t aPointerOrientation,
+                                     nsIObserver* aObserver)
+{
+  AutoObserverNotifier notifier(aObserver, "touchpoint");
+
+  if (!mGdkWindow) {
+    return NS_OK;
+  }
+
+  GdkEvent event;
+  memset(&event, 0, sizeof(GdkEvent));
+
+  static std::map<uint32_t, GdkEventSequence*> sKnownPointers;
+
+  auto result = sKnownPointers.find(aPointerId);
+  switch (aPointerState) {
+  case TOUCH_CONTACT:
+    if (result == sKnownPointers.end()) {
+      // GdkEventSequence isn't a thing we can instantiate, and never gets
+      // dereferenced in the gtk code. It's an opaque pointer, the only
+      // requirement is that it be distinct from other instances of
+      // GdkEventSequence*.
+      event.touch.sequence = (GdkEventSequence*)((size_t)aPointerId);
+      sKnownPointers[aPointerId] = event.touch.sequence;
+      event.type = GDK_TOUCH_BEGIN;
+    } else {
+      event.touch.sequence = result->second;
+      event.type = GDK_TOUCH_UPDATE;
+    }
+    break;
+  case TOUCH_REMOVE:
+    event.type = GDK_TOUCH_END;
+    if (result == sKnownPointers.end()) {
+      NS_WARNING("Tried to synthesize touch-end for unknown pointer!");
+      return NS_ERROR_UNEXPECTED;
+    }
+    event.touch.sequence = result->second;
+    sKnownPointers.erase(result);
+    break;
+  case TOUCH_CANCEL:
+    event.type = GDK_TOUCH_CANCEL;
+    if (result == sKnownPointers.end()) {
+      NS_WARNING("Tried to synthesize touch-cancel for unknown pointer!");
+      return NS_ERROR_UNEXPECTED;
+    }
+    event.touch.sequence = result->second;
+    sKnownPointers.erase(result);
+    break;
+  case TOUCH_HOVER:
+  default:
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  event.touch.window = mGdkWindow;
+  event.touch.time = GDK_CURRENT_TIME;
+
+  GdkDisplay* display = gdk_window_get_display(mGdkWindow);
+  GdkDeviceManager* device_manager = gdk_display_get_device_manager(display);
+  event.touch.device = gdk_device_manager_get_client_pointer(device_manager);
+
+  event.touch.x_root = aPointerScreenPoint.x;
+  event.touch.y_root = aPointerScreenPoint.y;
+
+  ScreenIntPoint pointInWindow = aPointerScreenPoint
+    - ViewAs<ScreenPixel>(WidgetToScreenOffset(),
+                          PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent);
+  event.touch.x = pointInWindow.x;
+  event.touch.y = pointInWindow.y;
+
+  gdk_event_put(&event);
+
+  return NS_OK;
+}
+#endif
+
 int32_t
 nsWindow::RoundsWidgetCoordinatesTo()
 {
     return GdkScaleFactor();
 }

--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -333,16 +333,25 @@ public:
                                                       uint32_t aNativeMessage,
                                                       double aDeltaX,
                                                       double aDeltaY,
                                                       double aDeltaZ,
                                                       uint32_t aModifierFlags,
                                                       uint32_t aAdditionalFlags,
                                                       nsIObserver* aObserver) override;
 
+#if GTK_CHECK_VERSION(3,4,0)
+    virtual nsresult SynthesizeNativeTouchPoint(uint32_t aPointerId,
+                                                TouchPointerState aPointerState,
+                                                ScreenIntPoint aPointerScreenPoint,
+                                                double aPointerPressure,
+                                                uint32_t aPointerOrientation,
+                                                nsIObserver* aObserver) override;
+#endif
+
     // HiDPI scale conversion
     gint GdkScaleFactor();
 
     // To GDK
     gint DevicePixelsToGdkCoordRoundUp(int pixels);
     gint DevicePixelsToGdkCoordRoundDown(int pixels);
     GdkPoint DevicePixelsToGdkPointRoundDown(LayoutDeviceIntPoint point);
     GdkRectangle DevicePixelsToGdkSizeRoundUp(LayoutDeviceIntSize pixelSize);