diff --git a/invesalius/data/cursor_actors.py b/invesalius/data/cursor_actors.py
index 61f6e10..3f1cb05 100644
--- a/invesalius/data/cursor_actors.py
+++ b/invesalius/data/cursor_actors.py
@@ -26,7 +26,6 @@ class CursorCircle:
         self.__build_actor()
         self.__calculate_area_pixels()
         
-        
     def __build_actor(self):
         """
         Function to plot the circle
@@ -113,15 +112,18 @@ class CursorCircle:
         px, py, pz = self.edition_position
         orient = self.orientation
         xs, ys, zs = self.spacing
+        abs_pixel = {"AXIAL": lambda x,y: (px + x / xs, py+(y/ys), pz),
+                     "CORONAL": lambda x,y: (px+(x/xs), py,
+                                            pz+(y/zs)),
+                     "SAGITAL": lambda x,y: (px, py+(x/ys),
+                                             pz+(y/zs))}
+        function_orientation = abs_pixel[orient]
         for pixel_0,pixel_1 in self.pixel_list:
             # The position of the pixels in this list is relative (based only on
             # the area, and not the cursor position).
             # Let's calculate the absolute position
             # TODO: Optimize this!!!!
-            abs_pixel = {"AXIAL": [px+pixel_0/xs, py+(pixel_1/ys), pz],
-                         "CORONAL": [px+(pixel_0/xs), py, pz+(pixel_1/zs)],
-                         "SAGITAL": [px, py+(pixel_0/ys), pz+(pixel_1/zs)]}
-            yield abs_pixel[orient]
+            yield function_orientation(pixel_0, pixel_1)
             
             
 #-------------------------------------------------------------------------------
diff --git a/invesalius/data/slice_.py b/invesalius/data/slice_.py
index 64595da..b4f4346 100644
--- a/invesalius/data/slice_.py
+++ b/invesalius/data/slice_.py
@@ -98,16 +98,19 @@ class Slice(object):
             self.ShowMask(index, value)
     #---------------------------------------------------------------------------
     def __erase_mask_pixel(self, pubsub_evt):
-        position = pubsub_evt.data
-        self.ErasePixel(position)
+        positions = pubsub_evt.data
+        for position in positions:
+            self.ErasePixel(position)
 
     def __edit_mask_pixel(self, pubsub_evt):
-        position = pubsub_evt.data
-        self.EditPixelBasedOnThreshold(position)
+        positions = pubsub_evt.data
+        for position in positions:
+            self.EditPixelBasedOnThreshold(position)
 
     def __add_mask_pixel(self, pubsub_evt):
-        position = pubsub_evt.data
-        self.DrawPixel(position)
+        positions = pubsub_evt.data
+        for position in positions:
+            self.DrawPixel(position)
     #---------------------------------------------------------------------------
     # END PUBSUB_EVT METHODS
     #---------------------------------------------------------------------------
@@ -191,7 +194,7 @@ class Slice(object):
         colour = self.imagedata.GetScalarRange()[0]# - 1 # Important to effect erase
         imagedata = self.current_mask.imagedata
         imagedata.SetScalarComponentFromDouble(x, y, z, 0, colour)
-        imagedata.Update()
+        #imagedata.Update()
         self.current_mask.edited_points[(x, y, z)] = colour
 
     def DrawPixel(self, position, colour=None):
@@ -201,7 +204,6 @@ class Slice(object):
         colour = self.imagedata.GetScalarRange()[1]
         imagedata = self.current_mask.imagedata
         imagedata.SetScalarComponentFromDouble(x, y, z, 0, colour)
-        imagedata.Update()
         self.current_mask.edited_points[(x, y, z)] = colour
 
     def EditPixelBasedOnThreshold(self, position):
diff --git a/invesalius/data/viewer_slice.py b/invesalius/data/viewer_slice.py
index cd5fc85..16e8d7b 100755
--- a/invesalius/data/viewer_slice.py
+++ b/invesalius/data/viewer_slice.py
@@ -195,8 +195,7 @@ class Viewer(wx.Panel):
 
         pixels = itertools.ifilter(self.TestOperationPosition,
                                    self.cursor.GetPixels())
-        for coord in pixels:
-            ps.Publisher().sendMessage(evt_msg, coord)
+        ps.Publisher().sendMessage(evt_msg, pixels)
 
         # FIXME: This is idiot, but is the only way that brush operations are
         # working when cross is disabled
@@ -219,10 +218,9 @@ class Viewer(wx.Panel):
         if self.mouse_pressed:
             pixels = itertools.ifilter(self.TestOperationPosition,
                                        self.cursor.GetPixels())
-            for coord in pixels:
-                ps.Publisher().sendMessage(evt_msg, coord)
+            ps.Publisher().sendMessage(evt_msg, pixels)
+            ps.Publisher().sendMessage('Update slice viewer')
         self.interactor.Render()
-        ps.Publisher().sendMessage('Update slice viewer')
 
     def OnCrossMove(self, obj, evt_vtk):
         coord = self.GetCoordinate()
--
libgit2 0.21.2