Fix OffsetBox custom picker

As with the custom picker, `Artist.contains` returns a boolean and a
dictionary in a tuple. This non-empty tuple is always true, so the
custom picker would always return True for any non-scroll event. It
would also lose the related dictionary.

Author: QuLogic

lib/matplotlib/offsetbox.py

@@ -1504,7 +1504,9 @@ def __init__(self, ref_artist, use_blit=False):
     @staticmethod
     def _picker(artist, mouseevent):
         # A custom picker to prevent dragging on mouse scroll events
-        return (artist.contains(mouseevent) and mouseevent.name != "scroll_event"), {}
+        if mouseevent.name != "scroll_event":
+            return artist.contains(mouseevent)
+        return False, {}
 
     # A property, not an attribute, to maintain picklability.
     canvas = property(lambda self: self.ref_artist.get_figure(root=True).canvas)