Thank you @jpgauthier for the nice comment. I'll take that in perspective, and come back with something solid to debate for tomorrow regarding the design. I really like the way you approach the solution, i'll have to look into it.

Meanwhile, would you be kind enough to review the way system is notified by his subitems and share your opinions on that matter ? I would like to have a second perspective on that as well.

Thanks and look for my next commit !