[plt-scheme] Keyword argument refactoring comments

Hi folks,

I've been reading bits and pieces of the new document for 4.x. I see
that in Slideshow, there is now one convenient slide function 'slide'
with keyword arguments for everything.

Did you enjoy cutting it over to using keyword arguments?

Did you ever find places where you thought keywords would be great,
but then turned out to be a bad idea?

Have you got any utilization of keyword argument idioms?

Best wishes,

Grant