@@ -1554,6 +1554,10 @@ class DotWidget(gtk.DrawingArea):

             self.queue_draw()

     def zoom_image(self, zoom_ratio, center=False, pos=None):

+        # Constrain zoom ratio to a sane range to prevent numeric instability.

+        zoom_ratio = min(zoom_ratio, 1E4)

+        zoom_ratio = max(zoom_ratio, 1E-6)

+

         if center:

             self.x = self.graph.width/2

             self.y = self.graph.height/2