Thanks to a few sentences worth of help from robert ginda on #mozilla, and tons of walking thru mozilla breakpoints to see how XUL wires up command handlers and executes them, clicking a button now results in the following output:
2005-07-20 20:30:14.653 layout Help! I've been clicked!
Button::ButtonPressed. return is a number
Button::ButtonPressed. return is an int
Button::ButtonPressed. return is a primitive
Button::ButtonPressed return is 17
The JS is:
So, what's the big deal? My layout engine is calling onclick handlers for button elements, that's what!
So, as a next step, I need to see if I can create an object that interfaces to C++ and provides logging services. Dumping output to stderr should be good enough. That way, I can write something like this:
logger.print("Button1Click: value is %d\n", 17);
Fun stuff :-)