Better scrollbar

[qwindelzorf]

The current scrollbar is rendered using the default windows widget. This really clashes with both the Windows Aero Glass border and the transparency effects added through the Ice IV patches.

Proposed is a scrollbar that is directly rendered, adhering to the transparency settings of the window. Graphically, it should be rendered much like scrollbars in the Chrome browser, as a narrow strip along the side of the pane, with a variable height grab handle. Optionally, the background of this scroll bar should be configurable to be transparent. There should also be an option to adjust transparency on mouse hover.