Abstract: A display assembly for posters or signs includes a cover frame having a clear sealed window at the front surface thereof. The display assembly is generally rectangular, the cover frame having four outwardly facing walls configured to slide into forwardly extending closely fitting walls extending from a one piece wall-mountable shroud-forming frame. Magnetic strips affixed to interior faces of the shroud-forming frame capture and hold an inserted cover frame, and the closely fitting shroud walls and immediately confronting cover frame walls serve to defeat the insertion of conventional tools to remove the cover when so emplaced. A special spatulate tool is configured with projections stressed to spring out of the plane of the blade in the relaxed state. The extensions are temporarily pressed flat during insertion, to spring outward when inserted to maximum depth into the assembly, the extensions when thus deployed confronting and engaging a rear portion of the cover frame.