Well, I understand that preset are not for what I’m looking for, so I’m back to using classes.
I still think, in the same way you have a color manager, you could have a “style manager” where you could have global styling of element.
The problem of course, is that there are already style that is applied to all elements through the graphical settings. And if I have to explain to a client that there is half the style in another interface, it doesn’t make sense.
I would expect to have the possibility to have a style manager, where I can pre-configure a style for an element and be able to modify it globally.
So, what is written in the FAQ is in fact wrong: no, there isn’t a solution for having a design tool to constantly tweak. Global block has the massive flaw that you can’t have a separate content and the use of classes is not a design tool, but a separate way of styling clashing with the element visual configuration (on the left, whatever is its name).