Launcher hides too soon

[Andrew]

The launcher hides when the mouse enters its right half (screencast attached). I expect it to hide only after the mouse has left the launcher completely.

This hiding threshold appears to be unaffected by the launcher icon size setting in System Settings ▸ Appearance; when I resize the launcher to 32 pixels wide, it still hides when I move the mouse beyond approximately 24 pixels from the edge of the screen.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: unity 7.0.0daily13.04.15-0ubuntu1
ProcVersionSignature: Ubuntu 3.8.0-18.28-generic 3.8.6
Uname: Linux 3.8.0-18-generic x86_64
ApportVersion: 2.9.2-0ubuntu8
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Thu Apr 18 06:18:53 2013
InstallationDate: Installed on 2013-04-06 (11 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20130402.1)
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)