fix: added comments to change

Stefan Mitic · Stefan Mitic · commit 2b2ec2a425b5 · 2020-04-04T19:25:59.000-04:00
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1401,6 +1401,7 @@ def __init__(self, name, canvas, x, y, button=None, key=None,
         self.step = step
         self.dblclick = dblclick
 
+        # super-init deferred to the end: callback errors if called before
         LocationEvent.__init__(self, name, canvas, x, y, guiEvent=guiEvent)
 
     def __str__(self):
@@ -1487,6 +1488,7 @@ def on_key(event):
     """
     def __init__(self, name, canvas, key, x=0, y=0, guiEvent=None):
         self.key = key
+        # super-init deferred to the end: callback errors if called before
         LocationEvent.__init__(self, name, canvas, x, y, guiEvent=guiEvent)
 
 
