IDL show line numbers

How to get the fancy viewer to show the line numbers is a bit tricky. Here's the link that gave me the answer:

https://www.exelisvis.com/language/en-US/UserCommunity/UserForums/forumid/27/postid/11936/scope/posts.aspx

IDL pause for debugging

IDL can be a royal pain sometimes, but the fact that it's a scripted language comes in handy when you have to debug. Aside from being able to just start typing in IDL commands right in the current focus if a proc hangs up, you can also set breakpoints and do stepping.

I never used the following info about doing it from the command line, but this has lots of useful features.

http://idlastro.gsfc.nasa.gov/idl_html_help/BREAKPOINT.html