I'm trying to test if a combo box field in FXRuby has changed, to warn
the user if they hit the Cancel button without saving their changes. 
Here's the code:

def cancelentry(sender, sel, ptr)

    @@stacbo.connect(SEL_CHANGED) do
     	 if MBOX_CLICKED_NO == FXMessageBox.question(self, MBOX_YES_NO,
        		"Cancel Update", "Changes made, cancel update?")
        		handle(nil, MKUINT(ID_CANCEL, SEL_COMMAND), nil)
       		return 1
	end
    end

end

The problem is that the code never displays the message box. What is
the proper way to code for a SEL_CHANGED event?

Thanks

John Reed