Ambiance, Radiance: make overlay scrollbars too look more like the ubuntu designed ones
- Remove the ugly background-gradient (and the highly rounded corners) - Show scrollbar track background only when using it (hovering or dragging) - Use some margin instead of resizing the scrollbar to get some proximity support on mouse enter as well (it will be shown when mouse is near) - Add some threshold pixels (2 now) for grabbing the slider - Add backdrop version Fixes: #1450747, #1493607 Approved by: Lars Uebernickel, PS Jenkins bot