Maria Luisa Poumaillou, whose eponymous rue Cambon store (recently relocated from around the corner on trendy rue du Mont Thabor) has been breaking new design names in Paris since it opened in 1988, may have two decades' fashion experience, but she's anything but old hat.  Her latest platform is a black and white stripe shop-in-shop in the middle of the designer floor at Paris's Printemps. The department store on blvd Haussmann has only recently taken the canvas tents off its façade after a major exterior renovation and interior revamp from Yabu Pushelberg, the Canadian duo who have also swept through Tiffany's and Bergdorf Goodman.  Now returned to its Belle Époque splendour on the outside, and with a gleaming black and white interior, Printemps is revving up its selection, notably with the installation of Poumaillou as Fashion Editor.  Rick Owens, Gareth Pugh, Christopher Kane, India's Manish Arora, L'Wren Scott, milliner Justin Smith, shoeman Pierre Hardy and even Victoria Beckham are in the Maria Luisa Printemps mix. Paris fashion avant-gardists came out on Saturday to toast the store before heading out  into the city's annual all-night bacchanal La Nuit Blanche.