Issue #18189: add test_delegator for Idle Delegator class.
Also change private dict used as a set to a set.
Issue #8515: Set __file__ when run file in IDLE. Backport 2c276d0553ff by
Andrew Svetlov, based on initial patch by Bruce Frederiksen.
Issue #7136: In the Idle File menu, "New Window" is renamed "New File".
Patch by Tal Einat, Roget Serwy, and Todd Rovito.
Issue #17097: Make multiprocessing ignore EINTR.