From the same bind file \bind "S-C-End" "buffer-end-select"
so I guess that that will do what you want too (shift-control-End).
That is it, thanks! Maybe, it would be worthy to add an entry in the Edit menu with the "Select All" option, likewise all word processors. Well, that is just a suggestion.
You can always copy ui/default.ui to your local .lyx directory and add the entry to your own, personal set of menus...
Angus