@@ -122,8 +122,7 @@ class DotWidget(Gtk.DrawingArea):

             return None

         return xdotcode

-    def set_dotcode(self, dotcode, filename=None):

-        self.openfilename = None

+    def _set_dotcode(self, dotcode, filename=None):

         # By default DOT language is UTF-8, but it accepts other encodings

         assert isinstance(dotcode, bytes)

         xdotcode = self.run_filter(dotcode)

@@ -135,6 +134,11 @@ class DotWidget(Gtk.DrawingArea):

             self.error_dialog(str(ex))

             return False

         else:

+            return True

+

+    def set_dotcode(self, dotcode, filename=None):

+        self.openfilename = None

+        if self._set_dotcode(dotcode, filename):

             if filename is None:

                 self.last_mtime = None

             else:

@@ -152,7 +156,7 @@ class DotWidget(Gtk.DrawingArea):

         if self.openfilename is not None:

             try:

                 fp = open(self.openfilename, 'rb')

-                self.set_dotcode(fp.read(), self.openfilename)

+                self._set_dotcode(fp.read(), self.openfilename)

                 fp.close()

             except IOError:

                 pass