A major Belgian arts institution has returned a painting held in its collection for decades to the descendants of a Jewish couple who had the work stolen by the Nazis. The Royal Museums of Fine Arts on Thursday handed over the painting “Flowers,” by German expressionist Lovis Corinth, to a lawyer representing the family, the Belga news agency reported. The painting of blue vase filled with pink flowers had belonged to Gustav and Emma Mayer before they fled their home in Nazi Germany to Belgium. Nazis looted their property and eventually, after the liberation of Belgium from its German occupier…