@@ -73,7 +73,8 @@ class DotWidget(Gtk.DrawingArea):

         self.add_events(Gdk.EventMask.POINTER_MOTION_MASK |

                         Gdk.EventMask.POINTER_MOTION_HINT_MASK |

                         Gdk.EventMask.BUTTON_RELEASE_MASK |

-                        Gdk.EventMask.SCROLL_MASK)

+                        Gdk.EventMask.SCROLL_MASK |

+                        Gdk.EventMask.SMOOTH_SCROLL_MASK)

         self.connect("motion-notify-event", self.on_area_motion_notify)

         self.connect("scroll-event", self.on_area_scroll_event)

         self.connect("size-allocate", self.on_area_size_allocate)

@@ -439,9 +440,13 @@ class DotWidget(Gtk.DrawingArea):

             self.zoom_image(self.zoom_ratio * self.ZOOM_INCREMENT,

                             pos=(event.x, event.y))

             return True

-        if event.direction == Gdk.ScrollDirection.DOWN:

+        elif event.direction == Gdk.ScrollDirection.DOWN:

             self.zoom_image(self.zoom_ratio / self.ZOOM_INCREMENT,

                             pos=(event.x, event.y))

+        else:

+            deltas = event.get_scroll_deltas()

+            self.zoom_image(self.zoom_ratio * (1 - deltas.delta_y / 10),

+                            pos=(event.x, event.y))

             return True

         return False