+(defun scroll-down-one ()
+ "Scroll text of current window downward one line.
+On attempt to scroll past end of buffer, `end-of-buffer' is signaled.
+On attempt to scroll past beginning of buffer, `beginning-of-buffer' is
+signaled.
+
+If `signal-error-on-buffer-boundary' is nil, attempts to scroll past buffer
+boundaries do not cause an error to be signaled."
+ (interactive "_")
+ (scroll-down-command 1))
+