That link was great!
“line.margin.visible=1” and “line.margin.width=1+” did the trick for
ver. 1.59 under WinXP
Embarasments:  The View menu would have allowed me to turn
line-nubers on and off (but with a default width).  The Help/SciTE
Help menu item would have gotten me to the file whose link you so
kindly provided.  I could have modified the relevant properties file
merely by clicking Options/Ruby properties (instead of opening it in
Notepad, the way I did.)
My worst embarasment: Yesterday I was toggling breakpoints on and off
by left-clicking in the margin opposite desired script lines. Today
that’s not working. I commented out the new options to no avail. Did I
accidentally destroy something in the options file, perhaps? Any
Again, thank you very much for your help.