Diplomacy is part theater, but a protocol blunder turned a top-level visit by European Union leaders to Turkey into drama on April 7. Ursula von der Leyen, the president of the EU executive arm, was left awkwardly standing as her colleague Charles Michel, the president of the council representing the bloc’s 27 members, and President Recep Tayyip Erdogan of Turkey took the only two available seats between the EU and Turkish flags. She ended up propped up by cushions on a side sofa several feet away, and lower than the two men.