diff --git a/invesalius/data/styles.py b/invesalius/data/styles.py
index 85446af..1698e2f 100644
--- a/invesalius/data/styles.py
+++ b/invesalius/data/styles.py
@@ -948,33 +948,41 @@ class WaterShedInteractorStyle(DefaultInteractorStyle):
         self.viewer.interactor.Render()
 
     def WOnScrollBackward(self, obj, evt):
+        iren = self.viewer.interactor
         viewer = self.viewer
-        iren = viewer.interactor
         if iren.GetControlKey():
-            if viewer.slice_.opacity > 0:
-                viewer.slice_.opacity -= 0.1
-                self.viewer.slice_.buffer_slices['AXIAL'].discard_vtk_mask()
-                self.viewer.slice_.buffer_slices['CORONAL'].discard_vtk_mask()
-                self.viewer.slice_.buffer_slices['SAGITAL'].discard_vtk_mask()
-                viewer.OnScrollBar()
+            mouse_x, mouse_y = iren.GetEventPosition()
+            render = iren.FindPokedRenderer(mouse_x, mouse_y)
+            slice_data = self.viewer.get_slice_data(render)
+            cursor = slice_data.cursor
+            size = cursor.radius * 2
+            size -= 1
+
+            if size > 0:
+                Publisher.sendMessage('Set watershed brush size', size)
+                cursor.SetPosition(cursor.position)
+                self.viewer.interactor.Render()
         else:
             self.OnScrollBackward(obj, evt)
 
-
     def WOnScrollForward(self, obj, evt):
+        iren = self.viewer.interactor
         viewer = self.viewer
-        iren = viewer.interactor
         if iren.GetControlKey():
-            if viewer.slice_.opacity < 1:
-                viewer.slice_.opacity += 0.1
-                self.viewer.slice_.buffer_slices['AXIAL'].discard_vtk_mask()
-                self.viewer.slice_.buffer_slices['CORONAL'].discard_vtk_mask()
-                self.viewer.slice_.buffer_slices['SAGITAL'].discard_vtk_mask()
-                viewer.OnScrollBar()
+            mouse_x, mouse_y = iren.GetEventPosition()
+            render = iren.FindPokedRenderer(mouse_x, mouse_y)
+            slice_data = self.viewer.get_slice_data(render)
+            cursor = slice_data.cursor
+            size = cursor.radius * 2
+            size += 1
+
+            if size <= 100:
+                Publisher.sendMessage('Set watershed brush size', size)
+                cursor.SetPosition(cursor.position)
+                self.viewer.interactor.Render()
         else:
             self.OnScrollForward(obj, evt)
 
-
     def OnBrushClick(self, obj, evt):
         if (self.viewer.slice_.buffer_slices[self.orientation].mask is None):
             return
diff --git a/invesalius/gui/task_slice.py b/invesalius/gui/task_slice.py
index b7471c1..255f0ad 100644
--- a/invesalius/gui/task_slice.py
+++ b/invesalius/gui/task_slice.py
@@ -902,6 +902,7 @@ class WatershedTool(EditionTools):
         self.SetAutoLayout(1)
 
         self.__bind_events_wx()
+        self.__bind_pubsub_evt()
 
 
     def __bind_events_wx(self):
@@ -912,6 +913,9 @@ class WatershedTool(EditionTools):
         self.btn_exp_watershed.Bind(wx.EVT_BUTTON, self.OnExpandWatershed)
         self.btn_wconfig.Bind(wx.EVT_BUTTON, self.OnConfig)
 
+    def __bind_pubsub_evt(self):
+        Publisher.subscribe(self._set_brush_size, 'Set watershed brush size')
+
     def ChangeMaskColour(self, pubsub_evt):
         colour = pubsub_evt.data
         self.gradient_thresh.SetColour(colour)
@@ -956,6 +960,10 @@ class WatershedTool(EditionTools):
         # Strangelly this is being called twice
         Publisher.sendMessage('Set watershed brush size',self.spin.GetValue())
 
+    def _set_brush_size(self, pubsub_evt):
+        size = pubsub_evt.data
+        self.spin.SetValue(size)
+
     def OnComboBrushOp(self, evt):
         brush_op = self.combo_brush_op.GetValue()
         Publisher.sendMessage('Set watershed operation', brush_op)
--
libgit2 0.21.2