bpo-33855: Still more edits and minimal tests for IDLE  (GH-7784)


Part 3 of 3, continuing PR GH-7689. This covers 14 idlelib modules and their tests,
rpc to zoomheight except for run (already done) and tooltip (being done separately).
(cherry picked from commit 4d92158f4c3917fc4fbfebff15224e74782abf79)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
diff --git a/Lib/idlelib/undo.py b/Lib/idlelib/undo.py
index 4332f10..f048994 100644
--- a/Lib/idlelib/undo.py
+++ b/Lib/idlelib/undo.py
@@ -359,8 +359,8 @@
     dump.pack(side='left')
 
 if __name__ == "__main__":
-    import unittest
-    unittest.main('idlelib.idle_test.test_undo', verbosity=2, exit=False)
+    from unittest import main
+    main('idlelib.idle_test.test_undo', verbosity=2, exit=False)
 
     from idlelib.idle_test.htest import run
     run(_undo_delegator)