bpo-29446: IDLE -- add explicit imports

[terryjreedy]

Stop depending on tkinter import *.

https://bugs.python.org/issue29446

[miss-islington]

Thanks @terryjreedy for the PR 🌮🎉.. I'm working now to backport this PR to: 3.7, 3.8.
🐍🍒⛏🤖

[bedevere-bot]

GH-14920 is a backport of this pull request to the 3.8 branch.

[bedevere-bot]

GH-14921 is a backport of this pull request to the 3.7 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot x86 Windows7 3.7 has failed when building commit aee260f.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/111/builds/1188) and take a look at the build logs.
4. Check if the failure is related to this commit (aee260f) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/111/builds/1188

Failed tests:

• test_idle

Failed subtests:

• test_showtip_on_mouse_enter_hover_delay - idlelib.idle_test.test_tooltip.HovertipTest

Summary of the results of the build (if available):

== Tests result: FAILURE then ENV CHANGED ==

384 tests OK.

10 slowest tests:

• test_multiprocessing_spawn: 14 min 7 sec
• test_zipfile: 8 min 10 sec
• test_concurrent_futures: 5 min 18 sec
• test_lzma: 2 min 50 sec
• test_regrtest: 2 min 46 sec
• test_asyncio: 2 min 29 sec
• test_tarfile: 2 min 22 sec
• test_decimal: 2 min 20 sec
• test_lib2to3: 2 min 9 sec
• test_venv: 1 min 49 sec

1 test altered the execution environment:
test_multiprocessing_spawn

31 tests skipped:
test_crypt test_curses test_dbm_gnu test_dbm_ndbm test_devpoll
test_epoll test_fcntl test_fork1 test_gdb test_grp test_ioctl
test_kqueue test_multiprocessing_fork
test_multiprocessing_forkserver test_nis test_openpty
test_ossaudiodev test_pipes test_poll test_posix test_pty test_pwd
test_readline test_resource test_spwd test_syslog
test_threadsignals test_wait3 test_wait4 test_xxtestfuzz
test_zipfile64

1 re-run test:
test_idle

Total duration: 56 min 48 sec

Click to see traceback logs

Traceback (most recent call last):
  File "D:\cygwin\home\db3l\buildarea\3.7.bolen-windows7\build\lib\idlelib\idle_test\test_tooltip.py", line 112, in test_showtip_on_mouse_enter_hover_delay
    self.assertFalse(tooltip.tipwindow and tooltip.tipwindow.winfo_viewable())
AssertionError: 1 is not false

[terryjreedy]

@taleinat @vstinner This buildbot IDLE test failure is a false positive that coincidentally occurred when testing another, trivial, IDLE change. What this report omits is that the test passed on the retest. The test that failed is a year old, written by Tal. (ENV CHANGED is from test_multiprocessing_spawn.)

Victor: Have you seen this failure before. Also, I thought the point of retest was to ignore transient failures like this?
Tal: Another test involving a mouse and live widget failed a year ago. bpo 31971. Perhaps there is some similarity.

[terryjreedy]

I forgot about seeing this before. See issue 35771.