Certainly! In the Display Settings page, the Code Listing Settings box has a field called "Code Prefix". In that box I have "<b><font color="red">&01;</font></b></p>&nbsp;". I like the line numbers to stand out, so I put 'em in red. The &01; bit tells PM to "put line number here".

Just in case anyone is interested (and for future reference), some other settings I'm using are:

• General site purtifications
  Display Settings / Theme Configuration / Theme Container: Perl-Blue Theme
• Keep vote button at UL corner of screen
  Display Settings / Style Sheet Settings / On-Site CSS Markup:
  

  input[name="sexisgreat"] {
    position: fixed;
    top: 0px;
    left: 0px;
    z-index:1;
    padding: 5px;
    border: 4px solid red;
  }
  [download]

• Make "readmore" stuff obvious
  Display Settings / Theme Configuration / Style Sheet Settings / On-Site CSS Markup:
  

  div.readmore { background-color: inherit;
    padding-left: 4px;
    border-left-width: 5px;
    border-left-color: #00ff00;
    border-left-style: solid;
    margin-left: -9px;
  }
  [download]

• Put the "I've Checked all these" button in the UL corner
  Display Settings / Style Sheet Settings / On-Site CSS Markup:
  

  input[name="viewedNewNodes"] {
    position: fixed;
    top: 0px;
    left: 0px;
    z-index:1;
    padding: 5px;
    border: 4px solid green;
  }
  [download]

• Make signatures stand out a bit
  Display Settings / Style Sheet Settings / On-Site CSS Markup:
  

  pmsig { background: #ff4040; }
  [download]

• I don't recall what this does for me
  It looks like I wanted preformatted text to wrap, but I've seen no evidence that it does that. But it might be doing something that I don't know about, otherwise, why would I have left it in? ;^D Display Settings / Style Sheet Settings / On-Site CSS Markup:
  

  pre { white-space: pre-wrap; }
  [download]

• Make certain monk's names prominent
  The first one is me, the next is the normal template I use. I change the background color for different groups of monks. Groups like "asks interesting questions", "makes amusing comments" and whatnot. IIRC, there's a way to ignore monks this way, but I forgot what it is, as I'm not using it.
  Display Settings / Style Sheet Settings / On-Site CSS Markup:

  .user-533863 { background: #CCFFCC; font-weight: bold }
  .user-###### { background: #FFCCCC; }
  [download]

• Computer-specific settings (like for $work or various home boxes
  Display Settings / Style Sheet Settings / Link to External CSS stylesheet:
  file:///path/used/on/all/my/computers/PM.css

None of this stuff is original, I've heard references on the chatterbox or noticed interesting nodes that provided these tips. I used to use a code formatter/syntax colorizer like the one tobyink references, but I abandoned that a few years ago when it went wonky on me and made page rendering take forever and a day.

Update: A few formatting tweaks I didn't notice before I clicked "create".

...roboticus

When your only tool is a hammer, all problems look like your thumb.

>  <b><font color="red">&01;</font></b></p>&nbsp;

Hm. .. I ignored that HTML tags could be injected too.

Enclosing line numbers in a span which is hidden by a onselect JS handler could be a solution for unintended selection.

Unfortunately no time for a prove of concept now.

FWIW, the source view in metacpan is pretty neat, no selection of line numbers and syntax highlighting.

Couldn't check yet how highlighting is implemented. ¹

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)}

PS: Je suis Charlie!

¹) looks Perltidy'ish

So your proposal has nothing to do with the default style sheet? Which is CSS?

I'm not saying that at all. I'm simply not web savvy enough to know how it would be done. I was guessing(!) that it could be done easily with a style sheet (CSS) which should be a relatively minor change. I don't think that the feature would help enough to warrant any code changes.

I tried viewing the page source for Re^2: Change default style sheet: add line numbers to see if I could figure out a way to modify my settings to make the line numbers not appear in a cut-and-paste, but wasn't able to do so in the limited time I had this morning. I may try again this evening, though.

Update: I forgot to mention--when I made the suggestion originally, I was thinking it was a CSS thing 'cause I totally forgot about the setting I actually used...until someone asked for how I got the line numbers to appear and I reviewed my settings.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

choroba, how do you know this is what roboticus is using in a css stylesheet? Thats quite a bit of javascript that isn't CSS