matplotlib
diff --git a/‎lib/matplotlib/transforms.py
Copy file name to clipboardExpand all lines: lib/matplotlib/transforms.py
+7-1Lines changed: 7 additions & 1 deletion b/‎lib/matplotlib/transforms.py
Copy file name to clipboardExpand all lines: lib/matplotlib/transforms.py
+7-1Lines changed: 7 additions & 1 deletion
@@ -169,7 +169,13 @@ def set_children(self, *children):
         # parents are destroyed, references from the children won't
         # keep them alive.
         for child in children:
-            child._parents[id(self)] = weakref.ref(self)
+            # pass a wek reference.  The second arg is a callback for
+            # when the weak ref is garbage collected, and will also
+            # remove the dictionary element, otherwise child._parents
+            # keeps growing for multiple draws.
+            ref = weakref.ref(self, lambda ref, sid=id(self),
+                                        target=child._parents: target.pop(sid))
+            child._parents[id(self)] = ref
 
     if DEBUG:
         _set_children = set_children