[R-SIG-Mac] Editor line-editing blank lines

[Roberto Osorio]

In the built-in edtor, if I try to recall previous commands for
editing, using the up arrow key, the edtor creates blank lines below
the previous command, so the cursor position moves up in the editing
window. For just one line editing, it is only a minor annoyance, but
when you try to edit and execute several previous commands, the space
at the bottom builds up until it may consume most of your editing
window, with the cursor ending up near the top. Would any settings
cure that?