overlay-scrollbar UI failure - can't move cursor to edge of screen, and then vertically to select orange scroll thumb

I am experiencing an Ubuntu overlay-scrollbar user interface failure. The cursor can't be moved to the edge of the screen, and then vertically to select the orange scroll thumb. Assuming the window is maximised, the standard sequence for selecting a scroll thumb (to perform a full document scroll operation) is;

1. move the mouse cursor to the right hand edge of screen
2. move the mouse cursor vertically towards the scroll thumb

This can't be done in Ubuntu. Moving the cursor diagonally is awkward and inefficient. Nobody selects an edge of screen object in this fashion. This is a fundamental UI design principle.

Thanks,

Richard

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: overlay-scrollbar 0.2.16+r359+13.10.20130826-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-15.25-generic 3.11.10
Uname: Linux 3.11.0-15-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
Date: Fri Apr 4 16:10:35 2014
InstallationDate: Installed on 2014-01-31 (62 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: overlay-scrollbar
UpgradeStatus: No upgrade log present (probably fresh install)