I daisy-chained components from @Nick_Bruscia (here) , from @davidsmavrov (here) , and from @JoshD (here) and it works !
Thanks fellows !
Recompute GH definition when Rhino file is changed.gh (6.9 KB)
It effectively recomputes the GH definition when a new Rhino file is opened.
Piece of cake 
@DavidRutten it would be really nice to have a component for that in GH 2.