The Desktop doesn’t scroll. The ScrollBars property is inherited from ContainerControl but should have been shadowed and hidden. When supported, ScrollBars.Both (and the other values) mean that it scrolls both directions, or vertically only, or horizontally, or never. It’s the equivalent of overflow-x: auto and overflow-y: auto.
To keep floating windows on the screen you can use the new property KeepOnScreen.
I set ScrollBars=Both (Wisej.Web.Desktop) and actually expect that the scrollbars appear as soon as I move a window outside the visible desktop area, for example … but nothing happens as you can see on the attached screenshot.