In the Hueys in Oz during the 70s, we still operated under full reporting when in civil airspace. Even VFR. Flight plans, accuracy to within 2 mins of a reporting point, or else amend it, clearances, blah blah. (Luckily Dick Smith changed all this when he took over CA$A).
As a result, we would write the flight plan on the Huey window in chinagraph, with reporting points, time intervals, estimates, amendments, clearances, squawk codes (though they were only used in some mil airspace.) The whole window on the copilot side would fill with chinagraph, and on a hot day the "lead" would melt in the pen and make a mess in the sleeve pocket and dribble on the window. On a long positioning flight, there would be a lot of writing on the window, removed with the back of the glove to make a nice colourful smear. Great for low sun angles.
I once saw that some wag had written "This window is in its third edition" in very neat writing. And they were all Staedtlers, inch-long coloured plastic rotating top, shiny clip, never had a string.