Display: add highlight support to scroll bar

[icewolfz]

Add a highlight support to the scroll bar like firefox and chrome that marks found search terms

quick way to do this would probably be use a cavas that overlays the scrollbar and ignores events allowing line to be draw to show where search highlights are, t find the search highlights on the bar it should be just a matter of (line index / total lines = %) and % * scrollbar height should get me the ~ x coord to draw a colored line to mark the search term