it's really annoying to have to leave the pen to scroll with the mouse because the scrolling bar is invisible. WHY?! i want to scroll with the bar on the side without putting away the pen to grab the mouse and scroll with the wheel. yes the scroll bar reappears when i scroll, but it's useless because it disappears after 2 seconds and does not appear in any way other than wheel scrolling with the mouse. VERY ANNOYING! scrolling should be available in few ways (like Adobe Acrobat) but here for some reason you only can scroll with the wheel. again, WHY?!