bug#10999: delete-other-windows should say why nothing happens sometimes

[jidanni]

X-Debbugs-Cc: rms@gnu.org

C-x 1 runs the command delete-other-windows

If not by default, then there should be some option settable to make it say
"There are no other windows, HOLMES",
if that indeed is the case.

Otherwise the user scratches his/her head wondering why nothing happens.

Same with

C-x o runs the command other-window.

You might think it is OK for nothing to happen.

But some of us think an explanation is due!

Did I submit this bug before? Yes.
So please reconsider.