People of all ages fell for the cute gnome-like alien at the center of Steven Spielberg’s 1982 movie “E.T. the Extra-Terrestrial.” But some fell extra hard; Katherine Bernhardt, who turned 7 the year the movie premiered, was smitten enough to paint portraits of E.T. in art school. In her latest show, “Done with Xanax,” she returns to him, pushing her distinctive fusion of Pop Art, Color Field and graffiti toward a more vulnerable, narrative expression and more complex painting process...