Here is a question I've been trying to find an answer to for 20 years: Why don't modern operating systems (e.g. MS-Windows, OS/X) still use the intuitive and space saving right-click 'pop-down' menu bars like their ancestors had (e.g. Amiga Workbench)?
The idea being that right-clicking (and holding) anywhere in the OS momentarily reveals a hidden context menu bar at the top of the screen. The menus and options available on this bar are context-sensitive, based on the object/app in focus at the time. This menu bar serves a dual purpose: it contains both context-specific menus as well as global system menus. The result is a larger, cleaner productivity space, with control still available at your fingertips.
Surely this is a better approach than the space consuming, always-visible application 'ribbon' bars and the various task bar/dock options plied upon us by most system vendors? The closest I've seen to this in recent years are various Ubuntu builds.