Two things I'd love to see improved (over the 12.04 video):
(a) as, the OP suggests, hide the arrows quicker when the mouse moves away. This solves the resize vs scroll issue, and makes the GUI feel faster to boot.
We can definitely play with the speed of animations and delays to see if this can reduce the conflict between the two operations.
(b) make the arrows thicker to compensate. This has the additonal advantage of improving support for laptop touchpads and touchscreens.
During the session at UDS we showed another exploration we are doing that is about adding a subtle friction to the horizontal movement of the pointer when passing over the scrollbar and, very important, when its speed is contained. While we are pleased with the results we just implemented it in a dummy prototype, such feature requires lot of low level work and might take some time to appear in the distro. If there is anyone who can help our engineer, please contact Cimi.
Touch screen are not supposed to use the overlay scrollbars but should scroll interacting directly with the content.
Thanks a lot for any feedback, chr