bpo-29446: tkinter 'import *' only imports what it should (GH-14864)
Add __all__ to tkinter.__init__ and submodules. Replace 'import *'
with explicit imports in some submodules.
diff --git a/Lib/tkinter/messagebox.py b/Lib/tkinter/messagebox.py
index 4a711fa..5f0343b 100644
--- a/Lib/tkinter/messagebox.py
+++ b/Lib/tkinter/messagebox.py
@@ -24,6 +24,10 @@
from tkinter.commondialog import Dialog
+__all__ = ["showinfo", "showwarning", "showerror",
+ "askquestion", "askokcancel", "askyesno",
+ "askyesnocancel", "askretrycancel"]
+
#
# constants