Thumb doesn't appear when approaching window from outside

[The Fiddler]

When approaching the overlay scollbar from inside the window, the scroll thumb appears as expected. However, when approaching the scrollbar from outside, the scroll thumb doens't appear - you need to first enter the window and then move towards the scrollbar again.

This behavior is highly unintuitive and should be fixed.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: overlay-scrollbar 0.1.12-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
Architecture: amd64
Date: Sat Jul 2 23:49:46 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: overlay-scrollbar
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Gabe Gorelick (gabegorelick)]

Still an issue in Precise.

This is a major usability issue in my opinion. This is very unintuitive behavior and has bitten me many times. It makes no sense that you have to mouse over the scrollbar from outside, then continue mousing to inside the window and back to the scrollbar area.