I have a hi res monitor, which makes the scroll bar very small when I am trying to design mobile versions of my site. It is hard to be sure I am selecting just the bar and not accidentally grabbing something else. A slightly wider target would improve the usability of the mobile design pages significantly. Thanks!
The scrollbar is okay with me for 2560px screen. I do think usage of page-up & page-down on the keyboard should be implemented though.