Some time ago I tried adding 'root.withdraw' to idle_test files that used tkinter to stop the widget flashing.  This never worked completely.  Now I know why -- it was the test.support import.  Knowing this now, I opened #27922 to add 'root.withdraw' where else needed.  With support.__init__ patched, idle tests in 3.6 are currently flash-free, with -ugui, and 2.7 and 3.5 should be also.  So unless there is objection by tomorrow, I will patch all three versions.  I want the import flash suppressed even when -ugui is passed.