A sliding screen frame for a closure assembly having an opening and an existing track for mounting a screen, the screen frame has framing sections with both inner and outer side edges, and a housing from which a screen is payed out and accumulated. The framing sections are adapted on the outer side edge to interfit with the existing track of the closure assembly to enable the sliding screen frame to slide across the opening of the closure assembly and the frame sections also being adapted on the inner side edge thereof to support and guide the free end of the screen between a fully payed out and a fully accumulated position. The screen frame has a mitreless corner connector for connecting adjacent framing sections without the need for mitre cuts thereof to establish continuity between the corner connector and the adjacent framing sections.