Earlier this week, I was reminded of a joke from my now distant childhood, which at the time was initially perplexing and then commensurately rib tickling. “When is a door not a door?” went the riddle. Answer: “When it is ajar.” The context for that half-century-plus reminiscence was the advent of the ninth rollout of the Jerusalem Biennale of Drawing, which kicked off on November 8 and will run through to February 7.As usual, the event takes place under the aegis of the Jerusalem Artists'