When pressing the "Show alternative spelling" shortcut it would be nice to be able to choose this unknown spelling with a number key (as the spelling alternatives) or to choose any element of this submenu with the arrow keys (the same behavior as for the auto completion list).
When I press the shortcut, (or select it from Edit > Show alternative spelling), I see little numbers and can navigate through the list with my keyboard.
By the way, I think the name "Show alternative spelling" should probably be changed. When I think of an alternative spelling, I think of: "color" vs "colour", etc. Also, if retained, it should probably be "Show alternative spellings".
How about something like: "Show alternatives" or "Show alternative forms"?
Surely I can see the numbers, but in many cases I prefer to add the "new" spelling - that remains unaccessible from the keyboard. Look:
Same for the other buttons (okay, some of them have their own shortcut).
It would be logical to have a similar "look&feel" (navigation with the arrow keys, at least for the spelling alternatives) here and for the auto-completion list.
Renaming would indeed make sense, as this menu offers more than spelling alternatives.