Cesarini/Thompson wxErlang chapter - how to write lastLineRange?

[Michael Turner]

I'm trying to work through the wx example in Cesarini & Thompson
(chapter "GUI programming with wxErlang".  On p.319 there are two
calls to a function lastLineRange on a wx TextCtrl.  The authors don't
supply this function, and I can't see any corresponding C++ member
function in the wxTextCtrl API here

  http://docs.wxwidgets.org/trunk/classwx_text_ctrl.html

It's looking like I have to write lastLineRange myself, to finish
working through this chapter.  Unless ... someone else has already run
into this roadblock, got around it, and can map out the detour for me? 
I'm sure I'll kludge something up, but it would be nice to do this one
more or less by the book, if possible.

-michael turner