How do I show line numbers?
The answer lies in the Margins. By default Margin 0 dispalys line numbers, but also by default it has a width of 0, effectively hiding it. Set margin 0's width to something like 20 to make it show up.
From Code:
scintilla.Margins[0].Width = 20;
Or in the designer expand Margins, then Margin0. Set the Width to 20.