So, what does it really do for you? It shows you the code in the active tab... in the scroll bar!!
To activate it, goto Tools > Options > Text Editor
To use it for all languages, proceed with All languages > Scroll Bars > Behavior
- Select Use map mode for vertical scroll bar
- Check the Show Preview Tooltip check box to get the preview on hoover.
- Select the look of the map, Off (to only have the preview tooltip), Narrow, Medium or Wide
Click OK and watch the magic happen! =)