Neither NeWS not Display PostScript were written in Objective-C, as far as I recall they were both written in C. They also both actually did implement substant

Neither NeWS not Display PostScript were written in Objective-C, as far as I recall they were both written in C. They also both actually did implement substantial portions of their respective window systems in PostScript. They didn't just use the PostScript imaging model with a conventional "shared memory backing store rectangles" window server model. NeXT's Display PostScript and Sun's NeWS split things differently: - NeWS had ways for the UI within a window to run "live" as threads within the window server process, and communicate with the app that owned the window - NeXT Display PostScript put almost all of the behavior of an application in the app process, which just received low-level events and sent PostScript drawing (and window management) commands to the window server. But in neither case was it just the PostScript imaging model being used; in both it was full-blown PostScript.