Line numbers for a JTextArea

hi i am making a text editor and i need to have a thin jpanel that goes down the side of my textarea which displays the line number.

does anyone have any idea how i would do this?

the API said something about offsets but i dont really understand it, please someone shed some light on the matter, thanks :)

[324 byte] By [boblettoj99a] at [2007-11-26 19:20:24]