If you don’t mind me asking… what’s the actual use case you want to address with this suggestion?
It seems your description is rather specific about how this should be implemented but I’m not getting the use case (not saying there is none).
There’s already an existing suggestion asking for an option to have users build some GUI designs / skins / themes. If that’s what you’re asking for, I suggest you comment/vote in that thread in order to avoid distracting votes – though I’m not sure I might have misunderstood what you’re aiming for.
