XTerm scrolling/refresh loses characters under compiz

[Tim]

Given:

1. An xterm (80x24 but any larger size works too) with
2a. 'less /var/log/Xorg.0.log' (or some other longish file) running in it, or
2b. 'cat /var/log/Xorg.0.log' (or some other longish file) in xterm's scrollback, and
3. compiz enabled (ticked in Cairo dock's 'Composite-Manager' icon)

Then when I (a) press ^L to refresh less's display, or (b) use shift page up/down to look at the output of cat, it often (95%) results in the top/bottom few lines failing to display.

These INDEPENDENTLY make xterm display all the characters it should, but adversely affect compiz's behaviour in other ways:

A. If I disable compiz (toggle with Cairo dock's icon).

B. If I set 'Compiz->Workarounds->General->Force full screen redraws on repaint'.

The 'Force synchronisation between X and GLX' option does nothing.

It looks to me like a synchronisation issue, as if xterm asks X to clear its bitmap (in response to less's request) but then starts repainting the characters it's received from less before before the clear operation starts - the first few lines are drawn but cleared by the (pending) clear. Some similar synchronisation clash obtains with the scroll operations.

I've just run the software update, so this machine is up to date.

Description: Ubuntu 11.10
Release: 11.10

less:
  Installed: 444-1ubuntu1
  Candidate: 444-1ubuntu1
  Version table:
 *** 444-1ubuntu1 0
        500 http://gb.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status

xterm:
  Installed: 271-1ubuntu2
  Candidate: 271-1ubuntu2
  Version table:
 *** 271-1ubuntu2 0
        500 http://gb.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status

compiz:
  Installed: 1:0.9.6+bzr20110929-0ubuntu6
  Candidate: 1:0.9.6+bzr20110929-0ubuntu6
  Version table:
 *** 1:0.9.6+bzr20110929-0ubuntu6 0
        500 http://gb.archive.ubuntu.com/ubuntu/ oneiric-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:0.9.6+bzr20110929-0ubuntu3 0
        500 http://gb.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages

[ 32.577] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[ 32.627] (II) Module fbdevhw: vendor="X.Org Foundation"
[ 32.627] compiled for 1.10.4, module version = 0.0.2
[ 32.627] ABI class: X.Org Video Driver, version 10.0
[ 32.628] (II) RADEON(0): Creating default Display subsection in Screen section
        "Default Screen Section" for depth/fbbpp 24/32
[ 32.628] (==) RADEON(0): Depth 24, (--) framebuffer bpp 32
[ 32.628] (II) RADEON(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps)
[ 32.628] (==) RADEON(0): Default visual is TrueColor
[ 32.628] (==) RADEON(0): RGB weight 888
[ 32.628] (II) RADEON(0): Using 8 bits per RGB (8 bit DAC)
[ 32.628] (--) RADEON(0): Chipset: "ATI Mobility Radeon 4500 Series" (ChipID = 0x9553)
[ 32.628] (II) RADEON(0): PCIE card detected
[ 32.628] drmOpenDevice: node name is /dev/dri/card0

[Tim (tim-launchpad-o)]

I forgot to mention: moving the window causes the missing text to appear, so this is a refresh/scroll issue, not a 'xterm has actually lost characters' issue.

[Launchpad Janitor (janitor)]

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

[Stephane Epardaud (stef-inforealm)]

I have the same problem.