My "favourite" (well, it's really a bit depressing) example is that I can boot AROS (an AmigaOS API reimplementation) in its Linux-hosted form on Linux, into Workbench (Amiga desktop) using a startup script that then automatically starts an Amiga GUI based text editor called FrexxEd on my laptop in less time than it takes a near pristine terminal-only Emacs install to start on the same machine.

If this was some incredibly primitive editor it'd be one thing, but it's an editor with a bytecode compiled C-like extension language build in, as well as AREXX support, so it's fully programmable.