Oracle SQL Developer: How do you turn on the line numbers?

Hi all

Having some kind of brain cramp here.  I'm using Oracle SQL Developer v4.1.2.20 and executing SQL and observing the query result displays an error that gives a line number.
Question:  How do you turn the line numbers on?  

I could have sworn it was View > Debugger... or View > Editor... but line numbers are not a choice.  
Context sensitive menus?

Thanks in advance.
Jim