Fix span selector onmove when we exit axes

blink1073 · blink1073 · commit f73682f2ff59 · 2015-08-07T09:11:20.000-05:00
diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
@@ -1518,6 +1518,9 @@ def _onmove(self, event):
         if self.pressv is None:
             return
         x, y = self._get_data(event)
+        if x is None:
+            return
+
         self.prev = x, y
         if self.direction == 'horizontal':
             v = x
