Implementing rulers in C# form

Answer 1

I'd built a custom control to do this in both X and Y location, and use two controls.

The control would have to override Paint() and use GDI methods to display the tick marks, it would then capture mouse events and update locations appropriately.

Answer 2

This is the best article I've found and used on the matter: http://www.codeproject.com/KB/miscctrl/ruler.aspx