Make scroll bar sliders more visible

I find it almost impossible to see the scroll bars sliders in order to be able to drag them to move around the source code.

This is especially true of the vertical scroll bar when there are source code markups for errors\warnings as these highlights run across the scroll bar region making it even harder to see the faint sliders.

I think a solid slider colour, e.g. solid black would be make life much easier, perhaps eventually having it as a preference option.