I use a length of pipe insulation over which to roll the window over, with the edge fed into the slot. It avoids it scratching itself and makes a reasonable size of it. (Learnt from previous owner, Tom Calcutt).
Tim
I use quite the same, a waterpool frite, but in the middle of the window in order to avoid to fold it.
https://www.decathlon.fr/frite-en-mousse-118-cm-id_8216134.html?LGWCODE=1508681;11737;809&utm_source=google_shopping&utm_term=Frite%20en%20mousse%20118%20cm&utm_medium=cpc&utm_campaign=ecommerce_shopbot&utm_source=google_shopping&utm_medium=cpc&utm_term=.&utm_campaign=PLA+-+High+Priority&utm_content=s3iprPMKv_dc|pcrid||pkw||pmt||pid|1508681&gclid=EAIaIQobChMIoPv8v9SW2AIV6p3tCh2gmQVxEAQYASABEgKWNvD_BwE
