In my old-fashioned Unix X environment, when I minimize a window, it becomes an actual icon on my root window instead of a taskbar representation. I have tools to automatically arrange these icons, including for my GNU Emacs windows. However, recently I made a mistake and told my window manager to put the GNU Emacs icons off screen. As a result, they disappeared entirely because X allows windows to be positioned off screen. I could have recovered the iconified Emacs in various ways, but I chose to terminate it and start over. It was just simpler in my state at that time.
https://utcc.utoronto.ca/~cks/space/blog/unix/XOffscreenIconMistake