I'm not really sure what you are talking about. Do you mean the scrollbar? If so, you don't need to click anywhere, that just provides a visual clue there is a scroll bar, simply use your scroll wheel on your mouse to move it. Of course if you don't have a scroll mouse it is your loss, but works great.
However I do have to say that for whatever reason they did make the little minus [-] button difficult to hit and the other way (control+ scroll wheel) while practical, is not discover-able.