This show, which will be on view at the Hunterdon Art Museum in Clinton until Jan. 8, is a passionate love letter to colored string and a playful, needle-sharp investigation of its creative possibilities. Mary Birmingham’s curation doesn’t feel daring, even though it is. It’s also quietly defiant. Even within the still-marginalized field of fiber art, embroidery is infrequently celebrated. The smart, subtly muscular “Thread Hijack” could help change that.