Annoying autobiographical detail, apropos of the square monitor discussion: this was my main computer screen from approx 2004-2010: Samsung LCD screen that can be used as a TV, or with a PC. As late as 2004 they were still imitating the old 4:3 CRT orientation. We were not yet conditioned to expect our lives to be a work of total widescreen 24/7 cinematic adventure with Dolby™ and Sensurround™.
Another addendum to that Rhizome "square monitor" discussion (briefly addresseed in Zoë Salditch's comment): surely the more seismic shift isn't from 4:3 to 16:9 but from landscape to portrait in everybody's smartphones. Have given serious thought to dropping my sidebar for that reason. (Drifting with the prevailing winds of orientation fashion.)