I've just tested fullscreen in Firefox on Oneiric. Most of the times it works fine, but sometimes the fullscreen looks just like the attached image, with a space between the top bar and the rest of Firefox window. Mouse position and mouse click action are not the same, they seem to have the exact difference as that "white" space on top, below the top bar. Dragging the top bar from there (the action to restore size before fullscreen) and then activating fullscreen again makes it work as expected.
I did not experience this bug before in Oneric (I only use it for testing until it becomes stable for production), but I have it for a while on Natty.
ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: unity 4.16.0-0ubuntu2
ProcVersionSignature: Ubuntu 3.0.0-11.18-generic 3.0.4
Uname: Linux 3.0.0-11-generic x86_64
.tmp.unity.support.test.0:
ApportVersion: 1.23-0ubuntu1
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,move,vpswitch,snap,place,grid,resize,mousepoll,imgpng,wall,regex,gnomecompat,unitymtgrabhandles,session,animation,fade,scale,workarounds,expo,ezoom,unityshell]
CompositorRunning: compiz
Date: Thu Sep 22 02:55:21 2011
DistUpgraded: Log time: 2011-09-02 02:45:07.701511
DistroCodename: oneiric
DistroVariant: ubuntu
DkmsStatus:
virtualbox-guest, 4.1.2, 3.0.0-10-generic, x86_64: installed
virtualbox-guest, 4.1.2, 3.0.0-11-generic, x86_64: installed
virtualbox-guest, 4.1.2, 3.0.0-9-generic, x86_64: installed
GraphicsCard: InnoTek Systemberatung GmbH VirtualBox Graphics Adapter [80ee:beef] (prog-if 00 [VGA controller])
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20110901)
Lsusb:
Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet
MachineType: innotek GmbH VirtualBox
ProcEnviron:
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-11-generic root=UUID=420633a3-843c-4bb5-af0b-3ba2ccc79f5a ro quiet splash vt.handoff=7
Renderer: Software
SourcePackage: unity
UpgradeStatus: Upgraded to oneiric on 2011-09-01 (20 days ago)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH
version.compiz: compiz 1:0.9.5.94+bzr2803-0ubuntu5
version.ia32-libs: ia32-libs N/A
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
Status changed to 'Confirmed' because the bug affects multiple users.