@thor those are even pretty similar to some of the german words "Mehrwertsteuer"-"merverdiavgift" :)

i said that with the special word for it because it is unfortunately rather common with those windows, therefore people invented a word for it.

side-question: are those windows common in norway? from my visits to scandinavia i've had the impression that they aren't that common, but that may be biased by my low-cost accomodations having old ones ;)