diff -r 3216bf5f711d -r 629680fb0582 GraphicViewer.py
--- a/GraphicViewer.py	Sat May 19 12:40:53 2012 +0200
+++ b/GraphicViewer.py	Mon May 21 09:59:44 2012 +0200
@@ -507,14 +507,15 @@
     ## Refresh the variable cursor.
     #  @param dc The draw canvas
     def RefreshCursor(self, dc=None):
-        if dc is None:
-            dc = wx.BufferedDC(wx.ClientDC(self.Canvas.canvas), self.Canvas._Buffer)
-        
-        # Erase previous time cursor if drawn
-        if self.LastCursor is not None:
-            self.DrawCursor(dc, *self.LastCursor)
-        
-        # Draw new time cursor
-        if self.CursorIdx is not None:
-            self.LastCursor = self.Datas[self.CursorIdx]
-            self.DrawCursor(dc, *self.LastCursor)
+        if self:
+            if dc is None:
+                dc = wx.BufferedDC(wx.ClientDC(self.Canvas.canvas), self.Canvas._Buffer)
+            
+            # Erase previous time cursor if drawn
+            if self.LastCursor is not None:
+                self.DrawCursor(dc, *self.LastCursor)
+            
+            # Draw new time cursor
+            if self.CursorIdx is not None:
+                self.LastCursor = self.Datas[self.CursorIdx]
+                self.DrawCursor(dc, *self.LastCursor)