cairo-dock-team team mailing list archive

[Rémi Denis-Courmont <remi@xxxxxxxxxx>]

For whatever reason, when Cairo-Dock is started Qt4-X11 starts using the
ARGB X11 visual, instead of normal RGB. I don't know why, but I assume
it's the intended behaviour. Indeed, all Qt4 widgets work fine that way.

VLC breaks because it tries to use a VLC Qt4 plugin video widget
directly through X11 (instead of libQt4). There, VLC (1.0 and older)
makes an incorrect assumption. It expects that the X11 visual of the Qt4
widget is the same as the visual of the root X11 window. That causes an
unexpected error in the X11 protocol. Then, Xlib calls the default error
handler, which aborts the VLC process.

Correct mt if I'm wrong. But I believe that the Qt4 API does not provide
a way to request a RGB visual instead of ARGB explicitly. So the any
application using QWidget::winId has to be ready to handle ARGB visuals.
VLC clearly fails here. From the wiki, I infer that Skype has the same
bug. For non-Qt4 apps like mplayer, I guess it's a similar problem,
though the choice or ARGB is not coming from Qt4-X11.

On the other hand, with an ARGB visual, I am afraid there is no way to
use XVideo anymore. At least neither of my XVideo adaptors list the ARGB
visual as supported. This means, even if the bug is fixed or worked
around in VLC, we cannot use the video overlay anymore, so rendering
will be a lot more CPU-demanding.

So in a sense, the proper solution would be for Qt4 to provide a way to
disable ARGB for some specific widgets. But to me, this would look more
like a new feature than a bug from libQt4.

-- 
VLC crashes if cairo-dock is installed in karmic alpha 4
https://bugs.launchpad.net/bugs/416294
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Dock Team, which is subscribed to Cairo-Dock Core.

Status in Cairo-Dock : Core: Invalid
Status in Qt: Confirmed
Status in VLC media player: Fix Committed
Status in “qt4-x11” package in Ubuntu: New
Status in “vlc” package in Ubuntu: Confirmed

Bug description:
Binary package hint: vlc

using a fresh install of Karmic 64bit Alpha 4 or the latest daily build with either the Karmic Desktop CD or Alternate CD for installations VLC fails to playback any type of video file is cario-dock is installed.

Notes: 

1) VLC works normally if installed on a fresh install of Karmic Alpha 4.
2) VLC fails to playback video after the package cairo-dock is installed

tested on HP pavilion laptop with intel CPU & Nvidia GPU and also tested on Toshiba Satelite laptop with Intel CPU & Intel GPU.