For me the worst example is Google Play Music on my phone. The scroll bar is there, but when you first open the app it's hidden underneath the pane at the top

For me the worst example is Google Play Music on my phone. The scroll bar is there, but when you first open the app it's hidden underneath the pane at the top of the screen - you have to scroll down by dragging the window before you can even see it. Then if the window contents are long enough, as in when you're looking at the entire song list, you can't actually grab the scroll indicator unless you get really lucky - the sensitive part of the bar is much smaller than the visual indicator. It flipping drives me mad.