There have been improvements to scroll bars; they just haven't really gained widespread acceptance.
On Genera, when you moused over the vertical scroll bar, a thin horizontal line appears across the screen at whatever x height your mouse was is. You could then click to tell the OS that you wanted to wanted to reflow the page using that x height as a reference point. If you pointed your mouse at the horizontal scroll bar, a vertical line appeared, and you could scroll left to right. This is sort of like pressing Control-l on Emacs. Instead scrolling and getting the desired result by trial and error, you could tell the OS exactly what you wanted to do. It was very useful for scrolling within pictures.
On Genera, when you moused over the vertical scroll bar, a thin horizontal line appears across the screen at whatever x height your mouse was is. You could then click to tell the OS that you wanted to wanted to reflow the page using that x height as a reference point. If you pointed your mouse at the horizontal scroll bar, a vertical line appeared, and you could scroll left to right. This is sort of like pressing Control-l on Emacs. Instead scrolling and getting the desired result by trial and error, you could tell the OS exactly what you wanted to do. It was very useful for scrolling within pictures.
You can see a video of this here [1] at 46:50.
[1] http://www.loper-os.org/?p=932