Unexpected scroll jump with new overlay scroll bars

In certain scenarios the new overlay scroll bars cause an unexpected jump to the middle of content, irrespective of current cursor position. I first noticed this in Evolution when switching between Inboxes I would always find myself in the middle of my emails instead of the top, where I was acting on current date-sorted messages. After not having any luck with gnome developers reproducing this, I had it happen in G-Edit and developed a simple way to reproduce this issue that happens fairly often to me in the 11.10 pre-release.

1) Open G-Edit maximized and load a text file long enough that it has page scroll (2 screens is fine)
2) Put the cursor in position 1 (col 1, row 1) at the top of the document (I don't think it matters, but my step)
3) Grab the overlay scroll bar and drag it to the bottom of the document, and overdrag it a bit so that the overlay actually disappears. In my case while grabbing the scroll bar (keeping the mouse button held) I just move around the lower right hand corner of my screen at the bottom of the scroll and the overlay disappears. It only shows the bug if you release the mouse after the overlay has disappeared while scrolled to the bottom.
4) The document is scrolled to the bottom and the overlay is gone
5) Click save (or probably any button in the toolbar at top of screen)
6) The scroll jumps to the middle of the document immediately

I have confirmed there is no way to reproduce this jump in 11.04 with non-overlay scroll bars. In Evolution, I find this behavior to be constantly annoying because I am always scrolling to the top or bottom as I change various sorts (date, name, subject, size, attachment, etc.).

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: unity 4.22.0-0ubuntu3
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
NonfreeKernelModules: fglrx
.tmp.unity.support.test.0:

ApportVersion: 1.23-0ubuntu3
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,commands,wall,place,session,grid,move,resize,gnomecompat,compiztoolbox,vpswitch,imgpng,snap,regex,unitymtgrabhandles,animation,fade,workarounds,expo,scale,unityshell]
CompositorRunning: compiz
Date: Wed Oct 12 15:06:32 2011
DistUpgraded: Log time: 2011-09-08 20:44:44.347842
DistroCodename: oneiric
DistroVariant: ubuntu
DkmsStatus:
 fglrx, 8.881, 3.0.0-12-generic, x86_64: installed
 vboxhost, 4.1.4, 3.0.0-12-generic, x86_64: installed
GraphicsCard:
 ATI Technologies Inc RS780M/RS780MN [Radeon HD 3200 Graphics] [1002:9612] (prog-if 00 [VGA controller])
   Subsystem: Hewlett-Packard Company Device [103c:30f2]
JockeyStatus:
 xorg:fglrx_updates - ATI/AMD proprietary FGLRX graphics driver (post-release updates) (Proprietary, Disabled, Not in use)
 xorg:fglrx - ATI/AMD proprietary FGLRX graphics driver (Proprietary, Enabled, In use)
MachineType: Hewlett-Packard HP Pavilion dv5 Notebook PC
ProcEnviron:
 LANGUAGE=en
 PATH=(custom, no user)
 LANG=en_US.utf8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-12-generic root=UUID=10f8a2ac-5ab7-43a2-bdf8-92eee349e09d ro quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: Upgraded to oneiric on 2011-09-09 (33 days ago)
dmi.bios.date: 08/19/2009
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.37
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 30F2
dmi.board.vendor: Quanta
dmi.board.version: 98.36
dmi.chassis.type: 10
dmi.chassis.vendor: Quanta
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.37:bd08/19/2009:svnHewlett-Packard:pnHPPaviliondv5NotebookPC:pvrRev1:rvnQuanta:rn30F2:rvr98.36:cvnQuanta:ct10:cvrN/A:
dmi.product.name: HP Pavilion dv5 Notebook PC
dmi.product.version: Rev 1
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.6+bzr20110929-0ubuntu5
version.fglrx-installer: fglrx-installer N/A
version.ia32-libs: ia32-libs 20090808ubuntu26
version.libdrm2: libdrm2 2.4.26-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3
version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1