I have done a couple of variations of this and the WHAT is not so difficult to solve but the WHERE is unfortunately. For the WHAT I simply use different CSS classes which use the display property (e.g "display: block" OR "display: none"). I use dropdowns in a specific SystemSettings BO that the user can customize and then I use BO rules to change the CSS class in a specific attribute (and that attribute is then used in the topmost (is that a word 🙂 ) DIV to determine if a particular "panel" is to be used / displayed. For multiuser apps you of course need a "settings" BO per user but except from that, the solution works and is simple.
The WHERE can probably also be solved with some additional CSS ninja tinkering and clever system design but nothing I have tried yet.
