What do you think about this? Only change: home shows scrollbars, colors are changed to use footer fill color and I can specify different Widths for background and knob.
Ok, first try was not so good. Now with much more decent width and some gradients in knob. @wizard123 do you think we should position the scrollbar in normal screens exactly as in your example? I mean background just next to the background rect, not on top of it.
I extended the default scrollviewer style to take RenderTransforms from the defining ListView (by adding a ResourceWrapper with a TranslateTransform to move the Scrollbar to the right side where needed).
Here are the results of the screens I modified and tested. I think we probably can't treat all ScrollViewers same way as with one style, so I took this way.
Extra points for an option to have the scroll bar fade in/out only when the user is moving around. Keeps the view clean but of course some designers/users may like it always on.