Normally you design a layout with a couple of placecholders (i.e. menu, title, left-content, right-content)
This way you can organize it how you want.
But when clicking something in the menu and you wanto to refresh left and right content on the same page, you need to add named containers/widgets etc. inside those placeholders and ajax-refresh them seperately.
This produces possible extra (unneeded) containers in the html.
My idea is be able to refresh the layout and you see the list of placeholders where you simply set if you want to refresh them or not.
so you end up with 1 ajax-refresh widget in the flow