Merge pull request matplotlib#4533 from matplotlib/revert-3769-master

Revert "made idle_event() in backend_bases.py return True"

Author: tacaswell

lib/matplotlib/backend_bases.py

@@ -1980,7 +1980,6 @@ def idle_event(self, guiEvent=None):
         s = 'idle_event'
         event = IdleEvent(s, self, guiEvent=guiEvent)
         self.callbacks.process(s, event)
-        return True
 
     def grab_mouse(self, ax):
         """