This is on up-to-date oneiric.
The recently-introduced orange rectangle used to highlight the selected desktop has round corners, but their curvature is, I suspect, hard-coded for a 2x2 desktop grid. The curves look bad on a 3x3 desktop grid, as depicted in the attached screenshots.
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,imgjpeg,copytex,compiztoolbox,decor,resize,resizeinfo,scale,move,imgpng,put,text,grid,shift,annotate,commands,regex,mousepoll,wall,gnomecompat,place,scaleaddon,animation,workarounds,session,expo,ezoom,unityshell]
CompositorRunning: compiz
Date: Wed Sep 21 10:02:24 2011
DistUpgraded: Log time: 2011-07-26 19:56:31.320447
DistroCodename: oneiric
DistroVariant: ubuntu
GraphicsCard:
Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 18) (prog-if 00 [VGA controller])
Subsystem: CLEVO/KAPOK Computer Device [1558:3100]
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
Lsusb:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 003: ID 04f2:b18d Chicony Electronics Co., Ltd
MachineType: System76, Inc. Lemur UltraThin
ProcEnviron:
LANGUAGE=en_GB:en
PATH=(custom, user)
LANG=en_GB.UTF-8
SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-11-generic root=UUID=33ac49be-0a52-411b-9654-4b7ccb572180 ro pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1 quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: Upgraded to oneiric on 2011-09-16 (5 days ago)
dmi.bios.date: 11/11/2010
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: CALPELLACRB.86C.0000.X.0000000000
dmi.board.asset.tag: Tag 12345
dmi.board.name: Lemur UltraThin
dmi.board.vendor: System76, Inc.
dmi.board.version: lemu2
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: System76, Inc.
dmi.chassis.version: lemu2
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrCALPELLACRB.86C.0000.X.0000000000:bd11/11/2010:svnSystem76,Inc.:pnLemurUltraThin:pvrlemu2:rvnSystem76,Inc.:rnLemurUltraThin:rvrlemu2:cvnSystem76,Inc.:ct10:cvrlemu2:
dmi.product.name: Lemur UltraThin
dmi.product.version: lemu2
dmi.sys.vendor: System76, Inc.
version.compiz: compiz 1:0.9.5.94+bzr2803-0ubuntu5
version.ia32-libs: ia32-libs 20090808ubuntu22
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
Hmm.. actually this seems hardware-dependent. My laptop with Intel graphics has the problem, but my desktop with an nvidia card (and the binary driver) displays the round corners correctly (on a 3x3 desktop as well). Might be an issue with how these round corners are drawn.