We first caught sight of one of Daniel Steegmann Mangrané's colorful curtains at Esther Schipper gallery's booth at Frieze New York last year, where we couldn't stop taking pictures of how nicely it framed the crowds rushing by on the other side. But we'd forgotten all about the Spanish-born, Brazilian-based artist until more of those curtains popped up on Sight Unseen contributor Su Wu's blog I'm Revolting last week. Steegmann appears to have a very philosophically rich practice, full of…