Of all the wondrous pieces on display at the recent Georgia O’Keeffe: Living Modern show at the Brooklyn Museum, amid the delicate hand-sewn blouses, freshly pressed wrap-dresses and austere Balenciaga coats, the item that seemed to capture the imagination most was an oft-mended denim apron, quietly folded in a display case. The apron seemed to conjure everything we admire about O’Keeffe — her self-sufficiency, her artisanship, her affection for the forthright and plain, and her innate elegance. That fascination was reflected in several New York collections, whether as true workwear styles in railroad denim or coated canvas, or in the myriad bib fronts, pinafore straps, tie waists and long layers.