[issue30780] IDLE: configdialog - add tests for ConfigDialog GUI.

[Terry J. Reedy]

Changes by Terry J. Reedy <tjreedy at udel.edu>:


----------
dependencies: +IDLE tests: don't modify tkinter.messagebox.
nosy: +csabella

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue30780>
_______________________________________