One of Sweden’s longest-established glassmakers is facing what could be a landmark legal challenge over €1m in royalties it has allegedly failed to pay to the creator of one its most famous pieces, in a test of an EU-wide “bestseller” right that was brought in to strengthen cultural creators against producers and publishers. Cloudy of hue and with a rustic texture that breaks the flickering tealight inside, the “snowball” glass lantern is a classic item of Swedish household design, as ubiquitous in the Nordic country’s homes as the Billy bookcase. With more than 15m sold worldwide, it has also been a reliable money-spinner for its manufacturer, Kosta Boda. Yet the sculptor Ann Wolff, whom the company credits as the inventor the snöbollen, has not seen a penny for her design classic since the mid-1980s, due to the time-limited contract she signed with the glassmaking company in the 1970s. Fifty years after she came up with her design, the Swedish visual artists organisation KRO is now suing Kosta Boda for unfair remuneration. German-born Wolff, 86, started …