Problem occurred when attribute xyz could not be pickled.
Since this is not trivial to selectively fix, block all
attributes (other than 'width'). IDLE does not access them
and they are private implementation details.
Tkinter is a fact, not necessarily a feature.
Reorganize editor key bindings in a logical order
and remove those that do not work, at least on Windows.
Improve shell bindings list.
test_configdialog.HighPageTest.test_highlight_target_text_mouse fails
if a line of the Highlight tab text sample is not visible. If so, bbox()
in click_char() returns None and the unpacking iteration fails.
This occurred on a Devuan Linux system. Fix by moving the
'see character' call inside click_char, just before the bbox call.
Also, reduce the click_char calls to just one per tag name and
replace the other nested function with a dict comprehension.