I always liked the arched window best. My kids watched Play School during that era when Colin Buchanan, Don Spencer, Noni Hazlehurst, Monica Trapaga, Benita Collings, Simon Burke, George Spartels, Philip Quast, etc. etc. etc. were presenters. John Hamblin had us all in stitches with his campy portrayals of Jack, and also Jill, in a nursery-rhyme sketch.
I don't remember seeing a diamond window ever; is that a recent innovation?