RE: purpose and usage of secondary-selection ???

[Drew Adams]

> PS (to developers): It would be nice if the emacs menus had some mention
> of secondary-selection, maybe some of its very basic functionality.  Not
> a big fan of mousing around in text processors or editors, but sometimes
> a menu can give a clue when I don't have one. :)

Please consider sending enhancement suggestions to the Emacs
developers, by doing `M-x report-emacs-bug' (that is also for
enhancements).

Wrt your menu idea:

There are few vanilla-Emacs commands that involve the secondary
selection.  Those that do exist I cannot imagine being useful
on a menu.

But I do agree with you that it can be helpful to discover
commands by exploring menus.

Library `second-sel.el' offers some more secondary-selection
commands, and some of them can be useful on a menu.  Library
`menu-bar+.el' adds these to the `Edit' menu, after `Paste':

 `Paste Secondary'
 `Move Secondary to Region'
 `Swap Region and Secondary'
 `Select Secondary as Region'

https://www.emacswiki.org/emacs/MenuBarPlus