Rule reminder
Dislocation moves a constituent with a resumptive clitic: 'Il libro, lo leggo stasera.' A cleft sentence uses 'è ... che/chi' to focus an element: 'È il libro che leggo stasera.' They serve different functions: dislocation marks a topic (shared info); a cleft sentence highlights new or contrasted information (focus).
'È Marco che ha rotto il vaso.' — What structure is this?