could you please try with the latest version (2.3) ?
I think it fixes the problem

2011/3/6 Luke <email address hidden>

> Public bug reported:
>
> Binary package hint: cairo-dock
>
> If cairo-dock is installed and has been run withing the same X session,
> Kdenlive running under compiz, with XV video output  will display a
> transparent monitor window, and no video, just transparency, until
> playback stops.Other window managers with xv output from kdenlive will
> give a blank monitor (background only) entirely during playback, just as
> the entire frame is transparent under compiz.
>
>  Using the X11 driver gives semi-transparent  (0<alpha<1) video with
> transparent borders under compiz, normal video playback under window
> managers other than compiz. Detaching the window returns the semi-
> transparent playback as though compiz were running.   In all cases the
> image returns to normal when playback stops.
>
>
> This report is posted on the Kdenlive website:
>
> http://www.kdenlive.org/forum/transparent-monitor-during-playback-
> uninstall-cairo-dock-and-dependencies
>
> "but the problem seems to be cause by cairo-dock. A number of other qt-
> base applications have known problems with it, that this workaround
> fixes:
>
> Others apps based on Qt4 like VirtualBox, Skype, VLC
> (for VLC, there was a bug only if the option 'Integrate video in interface'
> is enabled and vlc devs have added this workaround into the application)
> It's the same problem that (S)MPlayer, so you can use this command in order
> to launch your application, e.g.:
> export XLIB_SKIP_ARGB_VISUALS=1 && skype
> But you can also make a little script:
> Create a file with the extention ".sh" (launch_virtualbox.sh for example)
> Add these two lines :
> export XLIB_SKIP_ARGB_VISUALS=1
> virtualbox
> Change the right execution (Right clic on the file / Properties /
> Permissions / Execution => or directly :
> chmod +x launch_virtualbox.sh
> Use this file to execute this app.
> Or edit the launcher and use a command like this one:
> sh -c "env XLIB_SKIP_ARGB_VISUALS=1 kaffeine" "
>
> Unfortunately, this does not help in kdenlive(replacing "kaffeine"
> with"kdenlive"), where it has no effect and the transparency continues..
>
> Both SMplayer and Kaffeine also report video playback issues when cairo-
> dock is running:
>
>
> https://bugs.launchpad.net/cairo-dock-core/+bug/472112  declares that the
> problem is in qt-but in that case, the bug is being reported to appear in
>  opengl mode. With kdenlive the bug appears under both opengl and cairo
> backends. I've tested both, restarting X between tests.
>
> The only workaround I have found is to set cairo-dock not to start with
> the session and start it only when  not using Kdenlive. To use kdenlive,
> X must be restarted.  I just removed Docky so I could get rid of mono,
> now this...
>
> I am using cairo-dock_2.2.0~4-0ubuntu1 in Ubuntu Natty with compiz-
> unity, gnome-shell, kde, and icewm sessions all installed and working.
>
> ** Affects: cairo-dock (Ubuntu)
>     Importance: Undecided
>         Status: New
>
> --
> You received this bug notification because you are a member of Cairo-
> Dock Team, which is subscribed to cairo-dock in ubuntu.
> https://bugs.launchpad.net/bugs/729970
>
> Title:
>  Cairo-dock running or having been run  corrupts Kdenlive monitor
>  display
>
> Status in “cairo-dock” package in Ubuntu:
>  New
>
> Bug description:
>  Binary package hint: cairo-dock
>
>  If cairo-dock is installed and has been run withing the same X
>  session, Kdenlive running under compiz, with XV video output  will
>  display a transparent monitor window, and no video, just transparency,
>  until playback stops.Other window managers with xv output from
>  kdenlive will give a blank monitor (background only) entirely during
>  playback, just as the entire frame is transparent under compiz.
>
>   Using the X11 driver gives semi-transparent  (0<alpha<1) video with
>  transparent borders under compiz, normal video playback under window
>  managers other than compiz. Detaching the window returns the semi-
>  transparent playback as though compiz were running.   In all cases the
>  image returns to normal when playback stops.
>
>
>  This report is posted on the Kdenlive website:
>
>  http://www.kdenlive.org/forum/transparent-monitor-during-playback-
>  uninstall-cairo-dock-and-dependencies
>
>  "but the problem seems to be cause by cairo-dock. A number of other
>  qt-base applications have known problems with it, that this workaround
>  fixes:
>
>  Others apps based on Qt4 like VirtualBox, Skype, VLC
>  (for VLC, there was a bug only if the option 'Integrate video in
> interface' is enabled and vlc devs have added this workaround into the
> application)
>  It's the same problem that (S)MPlayer, so you can use this command in
> order to launch your application, e.g.:
>  export XLIB_SKIP_ARGB_VISUALS=1 && skype
>  But you can also make a little script:
>  Create a file with the extention ".sh" (launch_virtualbox.sh for example)
>  Add these two lines :
>  export XLIB_SKIP_ARGB_VISUALS=1
>  virtualbox
>  Change the right execution (Right clic on the file / Properties /
> Permissions / Execution => or directly :
>  chmod +x launch_virtualbox.sh
>  Use this file to execute this app.
>  Or edit the launcher and use a command like this one:
>  sh -c "env XLIB_SKIP_ARGB_VISUALS=1 kaffeine" "
>
>  Unfortunately, this does not help in kdenlive(replacing "kaffeine"
>  with"kdenlive"), where it has no effect and the transparency
>  continues..
>
>  Both SMplayer and Kaffeine also report video playback issues when
>  cairo-dock is running:
>
>
>  https://bugs.launchpad.net/cairo-dock-core/+bug/472112  declares that the
> problem is in qt-but in that case, the bug is being reported to appear in
>  opengl mode. With kdenlive the bug appears under both opengl and cairo
> backends. I've tested both, restarting X between tests.
>
>  The only workaround I have found is to set cairo-dock not to start
>  with the session and start it only when  not using Kdenlive. To use
>  kdenlive, X must be restarted.  I just removed Docky so I could get
>  rid of mono, now this...
>
>  I am using cairo-dock_2.2.0~4-0ubuntu1 in Ubuntu Natty with compiz-
>  unity, gnome-shell, kde, and icewm sessions all installed and working.
>
> _______________________________________________
> Mailing list: https://launchpad.net/~cairo-dock-team
> Post to     : <email address hidden>
> Unsubscribe : https://launchpad.net/~cairo-dock-team
> More help   : https://help.launchpad.net/ListHelp
>