Denise McGaha (denisemcgaha.com) may be the most in-demand interior designer you’ve never heard of. It’s not because the Dallas-based style-setter tries to avoid the spotlight—but her clients definitely do. “I work for a lot of sports figures, celebrities and corporate executives,” she says. “Their privacy is extremely important to them.” As it is for the newlywed homeowners of a 6,500-squarefoot limestone, cast-stone and glass residence that McGaha recently completed. It’s a house that practically demands attention, even though the people who live in it don’t ….