Thanks Jim. Your intuition was right - a call from within a function worked. It's annoying that the API isn't a little clearer about this but I am a noob and there are many things that remain unclear to me.

This may be a stupid question to some of you wizards, but can anyone tell me why this code does not work when pasted into a .rb file and dropped into the plugins directory?

straight out of the API...

# This is an example of an observer that watches tool interactions.
     class MyToolsObserver < Sketchup;;ToolsObserver
       def onActiveToolChanged(tools, tool_name, tool_id)
         UI.messagebox("onActiveToolChanged; " + tool_name.to_s)
       end
     end

     # Attach the observer.
     Sketchup.active_model.tools.add_observer(MyToolsObserver.new)

This is the resulting error...

@unknownuser said:

Error Loading File section_view.rb
undefined method `tools' for nil:NilClass

The script works perfectly however if I call the last part manually using the Ruby Console...

Sketchup.active_model.tools.add_observer(MyToolsObserver.new)

I suspect that my inability to understand this line of the class intro from the API is why I'm lost...

@unknownuser said:

To implement this observer, create a Ruby class of this type, override the desired methods, and add an instance of the observer to the Tools object.

WTF does override the desired methods mean!!??