Belgium’s fine arts museum has given a painting back to the descendants of an heir who was robbed by Nazi Germany before World War II. ‘Blumenstilleben,’ (Still Life with Flowers) painted in 1913 by German artist Lovis Corinth, was among dozens of artworks stolen by the Nazis from Gustav and Emma Mayer. They fled Frankfurt in 1938 to Belgium, where they settled down in the UK. After the war, the painting of pink flowers in a blue vase was exhibited in Belgium’s Royal Museums of Fine Arts because the authorities at the time failed to establish the original owner. In...