The initial patch, https://github.com/python/cpython/pull/1839, adds missing docstrings to textview and changes names to conform to PEP 8.  It was originally attached to #30290. I changed the bpo # in the title to 30495.  We will see if Belvedere bot corrects the linkage.

Cheryl: I forgot to mention something very important.  When we change externally accessible names  -- those of functions, classes, and attributes -- in module xyz (here textview), we must grep idlelib *recursively* to find modules and test modules that import xyz and then check all accesses to names within xyz to discover and fix any that we have broken.  (If everything were perfectly tested, discovery would be trivial: run test_idlelib.  But it is not, so we must grep.)

In this case, the change from textview.TextViewer.textView to textview.TextViewer.textview broke the  two copies of
       dialog._current_textview.textView.get('1.0', '1.end'))
in test_help_about.  Running test_idle, which should always be done before IDLE commits, would have caught this.  When Appveyor ran test_idle, it properly failed.  I am mystified the it did not in the Travis run.

I will change the attribute name to 'text' both to avoid confusion with the module name and since the value is a Text instance.  I will also change all the new uses of 'textview' as an attribute.