An SO question today got me to look more at SO questions and discussion, and this appears to be the most requested feature.

https://stackoverflow.com/questions/1432480/any-way-to-clear-pythons-idle-window - 2009, 129 upvotes, 32 answers (not all read yet)

... (15 other hits for [python-idle] clear screen)

https://stackoverflow.com/questions/54083355/how-to-clear-the-screen-in-idle-on-imac - 2019 today

So I want to revisit this after we do a bit more on squeezer.  I want to add 'Clear and Restart' to the Shell menu, as Raymond suggested, so I am inclined to 'clear and restart' this discussion by closing this issue and reopening #17632 as a followup.