[SOLVED]Transparent backgrounds are opaque black on Mageia 8

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[SOLVED]Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 11th, '20, 22:35

I have several programs that I wrote that use transparent backgrounds. I am running an up-to-date Cauldron system. Since a recent update of Qt5 to 5.15.2, which I installed on December 8, all of the backgrounds for the programs show up solid black. One of the programs is a simple clock. It used to look like this:

TransparencyBeforeUpdate.png
Clock before update
TransparencyBeforeUpdate.png (63.73 KiB) Viewed 912 times

The desktop image that it sits on is gray.

And now it looks like this:

TransparencyAfterUpdate.png
Clock after update
TransparencyAfterUpdate.png (60.41 KiB) Viewed 912 times

Same background image.

I suspect that this has something to do with the qt5 update, but I do not know that for sure.

To narrow down the problem, I created a very simple main window app in Qt Creator using their desktop app template, and I made the window transparent using the same technique that I used in my other programs, to wit:

Code: Select all
#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    // Make the MainWindow transparent
    this->setAttribute(Qt::WA_TranslucentBackground);
}

MainWindow::~MainWindow()
{
    delete ui;
}


The only thing I changed in the template created by Qt Creator is adding the this->setAttribute(Qt::WA_TranslucentBackground); call.

On my Mageia 7 computer, the window comes up transparent, but on the Mageia 8 computer it is opaque black.

I have searched the web and tried many suggestions that I found out there, but none of them fix the problem.

Last week, all of this was working fine, so I doubt that it is a programming error in my programs unless the Qt API has changed.

Is anyone else seeing a similar effect?

My inxi info:

Code: Select all
$ inxi -b
System:    Host: localhost Kernel: 5.9.12-desktop-1.mga8 x86_64 bits: 64 Desktop: KDE Plasma 5.20.4 Distro: Mageia 8 mga8
Machine:   Type: Desktop Mobo: ASUSTeK model: P5G41T-M LX PLUS v: Rev X.0x serial: <superuser/root required>
           BIOS: American Megatrends v: 0502 date: 10/21/2011
CPU:       Info: Dual Core Intel Core2 Duo E7300 [MCP] speed: 2362 MHz
Graphics:  Device-1: NVIDIA G94 [GeForce 9600 GT] driver: nvidia v: 340.108
           Display: x11 server: Mageia X.org 1.20.10 driver: nvidia,v4l resolution: 1920x1080~60Hz
           OpenGL: renderer: GeForce 9600 GT/PCIe/SSE2 v: 3.3.0 NVIDIA 340.108
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet driver: r8169
           Device-2: Realtek RTL-8100/8101L/8139 PCI Fast Ethernet Adapter driver: 8139too
           Device-3: Qualcomm Atheros AR9271 802.11n type: USB driver: ath9k_htc
Drives:    Local Storage: total: 465.76 GiB used: 28.61 GiB (6.1%)
Info:      Processes: 206 Uptime: 3h 57m Memory: 3.84 GiB used: 2.24 GiB (58.4%) Shell: Bash inxi: 3.1.09


I don't think that this is a Mageia problem, but I don't know who to report it to. Any tips or pointers are welcome.

Thanks
Banjo
(_)=='=~
Last edited by banjo on Jan 1st, '21, 02:25, edited 1 time in total.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby morgano » Dec 12th, '20, 21:26

I just have to compliment - that is the most beautiful looking desktop clock i have seen!
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 13th, '20, 01:08

Thank you, but I cannot take credit for the image.

I copped the clock face image from a conky script that I was running. The conky script was intermittently failing to run and was sucking 35% of my CPU, so I wrote a Qt5 program to display the clock. It now takes less than 3% of my CPU and always runs. My program uses the background image, but the program itself is 100% original by me.

The clock looked nicer when it had a transparent background. LOL.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 13th, '20, 05:55

FYI, I found the thread on the Mint forum where I got the original conky clock.

https://forums.linuxmint.com/viewtopic.php?f=212&t=30209&p=1429699&hilit=conky+clocks#p1429699

This person makes quite gorgeous clocks. The link should take you directly to the post with that download link, but if it doesn't you can find it in the post done at Sun Feb 11, 2018 3:56 pm.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 26th, '20, 16:31

Update:
My conky scripts are also no longer transparent. So it is not just the programs that I wrote that display this problem. Does conky running with own_window = true use Qt?

I ran my program in IceWm, and the transparency fails on that desktop as well. So plasma is not causing the issue.

I have posted the question on the Qt forum, but so far there are no responses there.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby JoesCat » Dec 27th, '20, 03:09

If your image renders fine in programs like GIMP, I would say leave your image "as-is" and consider the problem to be temporary for now as various upstream libraries continue to improve and also sort themselves out.
Upstream, the problem might be QT, plasma, wayland, X, gdk-pixbuf, and the various graphics drivers.

For example - I ran into similar blackness approximately around this date too while updating and testing-out Mageia8
https://bugs.mageia.org/show_bug.cgi?id=27884
My problem seems to now suggest the VESA driver, as the bug now disappeared with nouveau driver.

You can maybe narrow it down by trying, LXDE, and XFCE to exclude components like wayland.

Nice clock.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 27th, '20, 05:58

Thanks for the feedback. I have continued looking into it mostly for curiosity and learning how all this stuff works.

I think that I have absolved Qt from any responsibility for the transparency not working on my system.

I downloaded an example program from

https://github.com/datenwolf/codesamples/blob/master/samples/OpenGL/x11argb_opengl/x11argb_opengl.c

which I found at StackOverflow here

https://stackoverflow.com/questions/4052940/how-to-make-an-opengl-rendering-context-with-transparent-background

The program creates a window with a transparent background using GLX. I compiled this on my Mageia 7 system and it does create a window with a transparent background as expected. When I ran the program that I compiled on Mageia 7 on the Mageia 8 computer it made the window opaque black.

So I compiled the same code on my Mageia 8 computer, and the background is a black rectangle. No change to the code.

The program uses GLX to open the window, hence it does not use Qt at all, That indicates that the problem lies in the code that underpins the Qt software, not with Qt.

This would also explain why transparency also does not work in conky anymore either.

I suspect that it is a disconnect between X11 and the Nvidia driver. The other graphics seem to work OK.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 27th, '20, 15:32

I have reported this as a bug, although I suspect that my ancient hardware is partially to blame for the problem.

https://bugs.mageia.org/show_bug.cgi?id=27945
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 28th, '20, 17:58

I am continuing to look into this problem in conjunction with the bug report, https://bugs.mageia.org/show_bug.cgi?id=27945

I set the system up to use the Nouveau driver to see if the Nvidia driver is at fault.

Code: Select all
System:    Host: localhost Kernel: 5.10.3-desktop-1.mga8 x86_64 bits: 64 Desktop: KDE Plasma 5.20.4 Distro: Mageia 8 mga8
Machine:   Type: Desktop Mobo: ASUSTeK model: P5G41T-M LX PLUS v: Rev X.0x serial: <superuser required>
           BIOS: American Megatrends v: 0502 date: 10/21/2011
CPU:       Info: Dual Core Intel Core2 Duo E7300 [MCP] speed: 2659 MHz
Graphics:  Device-1: NVIDIA G94 [GeForce 9600 GT] driver: nouveau v: kernel
           Display: x11 server: Mageia X.org 1.20.10 driver: nouveau,v4l resolution: 1920x1080~60Hz
           OpenGL: renderer: NV94 v: 3.3 Mesa 20.3.1

The transparency still fails. All I get for transparent backgrounds is an opaque black rectangle. That is what I get when I run my GLX window program as well, which bypasses Qt. When I run that program, I can set the color of the transparent background to something other than black, and the color that I set shows up. But the alpha channel is ignored. The background is opaque.

So, the Nvidia proprietary driver is not at fault since I am not running that driver any more. It now looks like X11 might be at fault, although I am not aware of how I can isolate that. It could also be something related to my antique Nvidia card. I don't know if the hardware can fail in such a way or not. I am seeing no odd effects from the graphics card other than the inability to do translucent windows. I checked when I installed Nouveau, and translucency was enabled.

I am not seeing any odd effects in any of the Mageia tools. It is just the transparent backgrounds in the applications.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Dec 31st, '20, 20:39

I am still trying to fix this problem. Because of some suggestions on the bug tracker, https://bugs.mageia.org/show_bug.cgi?id=27945, I installed XFCE and ran my tests on that Desktop. On XFCE the transparency works fine. So that would imply that something changed in Plasma on Dec. 8 when I installed a large Plasma update.

Code: Select all
[root@localhost ~]# urpmi --auto-update
    http://mirror.math.princeton.edu/pub/mageia/distrib/cauldron/x86_64/media/core/release/media_info/20201208-200242-synthesis.hdlist.cz
updated medium "Core Release"                                                                                                                       
medium "Core Updates" is up-to-date
    http://mirror.math.princeton.edu/pub/mageia/distrib/cauldron/x86_64/media/nonfree/release/media_info/20201208-112003-synthesis.hdlist.cz
updated medium "Nonfree Release"                                                                                                                   
medium "Nonfree Updates" is up-to-date
medium "Tainted Release" is up-to-date
medium "Tainted Updates" is up-to-date
medium "google-chrome" is up-to-date
To satisfy dependencies, the following packages are going to be installed:
  Package                        Version      Release       Arch   
(medium "Core Release")
  attica                         5.76.0       1.mga8        x86_64 
  baloo                          5.76.0       1.mga8        x86_64 
  bluedevil                      5.20.4       1.mga8        x86_64 
  bluez-qt                       5.76.0       1.mga8        x86_64 
  breeze                         5.20.4       1.mga8        x86_64 
  breeze-common                  5.20.4       1.mga8        noarch 
  breeze-gtk                     5.20.4       1.mga8        x86_64 
  breeze-icons                   5.76.0       1.mga8        noarch 
  frameworkintegration           5.76.0       1.mga8        x86_64 
  gcc                            10.2.1       0.20201205.1> x86_64 
  gcc-c++                        10.2.1       0.20201205.1> x86_64 
  gcc-cpp                        10.2.1       0.20201205.1> x86_64 
  gcc-plugins                    10.2.1       0.20201205.1> x86_64 
  gdk-pixbuf2.0                  2.42.2       1.mga8        x86_64 
  kactivities                    5.76.0       1.mga8        x86_64 
  kactivities-stats              5.76.0       1.mga8        x86_64 
  kactivitymanagerd              5.20.4       1.mga8        x86_64 
  karchive                       5.76.0       1.mga8        x86_64 
  kauth                          5.76.0       1.mga8        x86_64 
  kbookmarks                     5.76.0       1.mga8        x86_64 
  kcalendarcore                  5.76.0       1.mga8        x86_64 
  kcmutils                       5.76.0       1.mga8        x86_64 
  kcodecs                        5.76.0       1.mga8        x86_64 
  kcompletion                    5.76.0       1.mga8        x86_64 
  kconfig                        5.76.0       1.mga8        x86_64 
  kconfigwidgets                 5.76.0       1.mga8        x86_64 
  kcontacts                      5.76.0       1.mga8        x86_64 
  kcoreaddons                    5.76.0       1.mga8        x86_64 
  kcrash                         5.76.0       1.mga8        x86_64 
  kdav                           5.76.0       1.mga8        x86_64 
  kde-cli-tools                  5.20.4       1.mga8        x86_64 
  kde-gtk-config                 5.20.4       1.mga8        x86_64 
  kdeclarative                   5.76.0       1.mga8        x86_64 
  kdecoration                    5.20.4       1.mga8        x86_64 
  kded                           5.76.0       1.mga8        x86_64 
  kdelibs4support                5.76.0       1.mga8        x86_64 
  kdeplasma-addons               5.20.4       1.mga8        x86_64 
  kdesu                          5.76.0       1.mga8        x86_64 
  kdnssd                         5.76.0       1.mga8        x86_64 
  kdoctools                      5.76.0       1.mga8        x86_64 
  kemoticons                     5.76.0       1.mga8        x86_64 
  kfilemetadata                  5.76.0       1.mga8        x86_64 
  kgamma5                        5.20.4       1.mga8        x86_64 
  kglobalaccel                   5.76.0       1.mga8        x86_64 
  kguiaddons                     5.76.0       1.mga8        x86_64 
  kholidays                      5.76.0       1.mga8        x86_64 
  khotkeys                       5.20.4       1.mga8        x86_64 
  khtml                          5.76.0       1.mga8        x86_64 
  ki18n                          5.76.0       1.mga8        x86_64 
  kiconthemes                    5.76.0       1.mga8        x86_64 
  kidletime                      5.76.0       1.mga8        x86_64 
  kimageformats                  5.76.0       1.mga8        x86_64 
  kinfocenter                    5.20.4       1.mga8        x86_64 
  kinit                          5.76.0       1.mga8        x86_64 
  kio                            5.76.0       1.mga8        x86_64 
  kio-handbook                   5.76.0       1.mga8        noarch 
  kirigami                       5.76.0       1.mga8        x86_64 
  kitemmodels                    5.76.0       1.mga8        x86_64 
  kitemviews                     5.76.0       1.mga8        x86_64 
  kjobwidgets                    5.76.0       1.mga8        x86_64 
  kmenuedit                      5.20.4       1.mga8        x86_64 
  knewstuff                      5.76.0       1.mga8        x86_64 
  knotifications                 5.76.0       1.mga8        x86_64 
  knotifyconfig                  5.76.0       1.mga8        x86_64 
  kpackage                       5.76.0       1.mga8        x86_64 
  kparts                         5.76.0       1.mga8        x86_64 
  kpeople                        5.76.0       1.mga8        x86_64 
  kpty                           5.76.0       1.mga8        x86_64 
  kquickcharts                   5.76.0       1.mga8        x86_64 
  kross                          5.76.0       1.mga8        x86_64 
  krunner                        5.76.0       1.mga8        x86_64 
  kscreen                        5.20.4       1.mga8        x86_64 
  kscreenlocker                  5.20.4       1.mga8        x86_64 
  kservice                       5.76.0       1.mga8        x86_64 
  ksysguard                      5.20.4       1.mga8        x86_64 
  ktexteditor                    5.76.0       1.mga8        x86_64 
  ktextwidgets                   5.76.0       1.mga8        x86_64 
  kunitconversion                5.76.0       1.mga8        x86_64 
  kwallet                        5.76.0       1.mga8        x86_64 
  kwallet-pam                    5.20.4       1.mga8        x86_64 
  kwayland                       5.76.0       1.mga8        x86_64 
  kwayland-server                5.20.4       1.mga8        x86_64 
  kwidgetsaddons                 5.76.0       1.mga8        x86_64 
  kwin                           5.20.4       1.mga8        x86_64 
  kwin-common                    5.20.4       1.mga8        x86_64 
  kwindowsystem                  5.76.0       1.mga8        x86_64 
  kxmlgui                        5.76.0       1.mga8        x86_64 
  lib64breezecommon5_5           5.20.4       1.mga8        x86_64 
  lib64colorcorrect5             5.20.4       1.mga8        x86_64 
  lib64gdk_pixbuf-gir2.0         2.42.2       1.mga8        x86_64 
  lib64gdk_pixbuf2.0_0           2.42.2       1.mga8        x86_64 
  lib64kcmkwincommon5            5.20.4       1.mga8        x86_64 
  lib64kdecorations2_5           5.20.4       1.mga8        x86_64 
  lib64kdecorations2private7     5.20.4       1.mga8        x86_64 
  lib64kf5activities5            5.76.0       1.mga8        x86_64 
  lib64kf5activitiesstats1       5.76.0       1.mga8        x86_64 
  lib64kf5archive5               5.76.0       1.mga8        x86_64 
  lib64kf5attica5                5.76.0       1.mga8        x86_64 
  lib64kf5auth5                  5.76.0       1.mga8        x86_64 
  lib64kf5authcore5              5.76.0       1.mga8        x86_64 
  lib64kf5baloo5                 5.76.0       1.mga8        x86_64 
  lib64kf5balooengine5           5.76.0       1.mga8        x86_64 
  lib64kf5bluezqt6               5.76.0       1.mga8        x86_64 
  lib64kf5bookmarks5             5.76.0       1.mga8        x86_64 
  lib64kf5calendarcore5          5.76.0       1.mga8        x86_64 
  lib64kf5calendarevents5        5.76.0       1.mga8        x86_64 
  lib64kf5codecs5                5.76.0       1.mga8        x86_64 
  lib64kf5completion5            5.76.0       1.mga8        x86_64 
  lib64kf5configcore5            5.76.0       1.mga8        x86_64 
  lib64kf5configgui5             5.76.0       1.mga8        x86_64 
  lib64kf5configwidgets5         5.76.0       1.mga8        x86_64 
  lib64kf5contacts5              5.76.0       1.mga8        x86_64 
  lib64kf5coreaddons5            5.76.0       1.mga8        x86_64 
  lib64kf5crash5                 5.76.0       1.mga8        x86_64 
  lib64kf5dav5                   5.76.0       1.mga8        x86_64 
  lib64kf5dbusaddons5            5.76.0       1.mga8        x86_64 
  lib64kf5declarative5           5.76.0       1.mga8        x86_64 
  lib64kf5dnssd5                 5.76.0       1.mga8        x86_64 
  lib64kf5doctools5              5.76.0       1.mga8        x86_64 
  lib64kf5emoticons5             5.76.0       1.mga8        x86_64 
  lib64kf5filemetadata3          5.76.0       1.mga8        x86_64 
  lib64kf5globalaccel5           5.76.0       1.mga8        x86_64 
  lib64kf5globalaccelprivate5    5.76.0       1.mga8        x86_64 
  lib64kf5guiaddons5             5.76.0       1.mga8        x86_64 
  lib64kf5holidays5              5.76.0       1.mga8        x86_64 
  lib64kf5i18n5                  5.76.0       1.mga8        x86_64 
  lib64kf5iconthemes5            5.76.0       1.mga8        x86_64 
  lib64kf5idletime5              5.76.0       1.mga8        x86_64 
  lib64kf5itemmodels5            5.76.0       1.mga8        x86_64 
  lib64kf5itemviews5             5.76.0       1.mga8        x86_64 
  lib64kf5jobwidgets5            5.76.0       1.mga8        x86_64 
  lib64kf5js5                    5.76.0       1.mga8        x86_64 
  lib64kf5jsapi5                 5.76.0       1.mga8        x86_64 
  lib64kf5kcmutils5              5.76.0       1.mga8        x86_64 
  lib64kf5kdelibs4support5       5.76.0       1.mga8        x86_64 
  lib64kf5khtml5                 5.76.0       1.mga8        x86_64 
  lib64kf5kiocore5               5.76.0       1.mga8        x86_64 
  lib64kf5kiofilewidgets5        5.76.0       1.mga8        x86_64 
  lib64kf5kiogui5                5.76.0       1.mga8        x86_64 
  lib64kf5kiontlm5               5.76.0       1.mga8        x86_64 
  lib64kf5kiowidgets5            5.76.0       1.mga8        x86_64 
  lib64kf5kirigami2_5            5.76.0       1.mga8        x86_64 
  lib64kf5krosscore5             5.76.0       1.mga8        x86_64 
  lib64kf5kscreen7               5.20.4       1.mga8        x86_64 
  lib64kf5networkmanagerqt6      5.76.0       1.mga8        x86_64 
  lib64kf5newstuff5              5.76.0       1.mga8        x86_64 
  lib64kf5newstuffcore5          5.76.0       1.mga8        x86_64 
  lib64kf5notifications5         5.76.0       1.mga8        x86_64 
  lib64kf5notifyconfig5          5.76.0       1.mga8        x86_64 
  lib64kf5package5               5.76.0       1.mga8        x86_64 
  lib64kf5parts5                 5.76.0       1.mga8        x86_64 
  lib64kf5people5                5.76.0       1.mga8        x86_64 
  lib64kf5peoplebackend5         5.76.0       1.mga8        x86_64 
  lib64kf5peoplewidgets5         5.76.0       1.mga8        x86_64 
  lib64kf5plasma5                5.76.0       1.mga8        x86_64 
  lib64kf5plasmaquick5           5.76.0       1.mga8        x86_64 
  lib64kf5prison5                5.76.0       1.mga8        x86_64 
  lib64kf5pty5                   5.76.0       1.mga8        x86_64 
  lib64kf5purpose5               5.76.0       1.mga8        x86_64 
  lib64kf5purposewidgets5        5.76.0       1.mga8        x86_64 
  lib64kf5quickaddons5           5.76.0       1.mga8        x86_64 
  lib64kf5runner5                5.76.0       1.mga8        x86_64 
  lib64kf5service5               5.76.0       1.mga8        x86_64 
  lib64kf5solid5                 5.76.0       1.mga8        x86_64 
  lib64kf5sonnetcore5            5.76.0       1.mga8        x86_64 
  lib64kf5sonnetui5              5.76.0       1.mga8        x86_64 
  lib64kf5style5                 5.76.0       1.mga8        x86_64 
  lib64kf5su5                    5.76.0       1.mga8        x86_64 
  lib64kf5syntaxhighlighting5    5.76.0       1.mga8        x86_64 
  lib64kf5texteditor5            5.76.0       1.mga8        x86_64 
  lib64kf5textwidgets5           5.76.0       1.mga8        x86_64 
  lib64kf5threadweaver5          5.76.0       1.mga8        x86_64 
  lib64kf5unitconversion5        5.76.0       1.mga8        x86_64 
  lib64kf5wallet5                5.76.0       1.mga8        x86_64 
  lib64kf5walletbackend55        5.76.0       1.mga8        x86_64 
  lib64kf5wayland5               5.76.0       1.mga8        x86_64 
  lib64kf5webkit5                5.76.0       1.mga8        x86_64 
  lib64kf5widgetsaddons5         5.76.0       1.mga8        x86_64 
  lib64kf5windowsystem5          5.76.0       1.mga8        x86_64 
  lib64kf5xmlgui5                5.76.0       1.mga8        x86_64 
  lib64kfontinst5                5.20.4       1.mga8        x86_64 
  lib64kfontinstui5              5.20.4       1.mga8        x86_64 
  lib64khotkeysprivate5          5.20.4       1.mga8        x86_64 
  lib64kscreenlocker5            5.20.4       1.mga8        x86_64 
  lib64ksgrd9                    5.20.4       1.mga8        x86_64 
  lib64ksignalplotter9           5.20.4       1.mga8        x86_64 
  lib64ksysguardformatter1       5.20.4       1.mga8        x86_64 
  lib64ksysguardsensorfaces1     5.20.4       1.mga8        x86_64 
  lib64ksysguardsensors1         5.20.4       1.mga8        x86_64 
  lib64kwaylandserver5           5.20.4       1.mga8        x86_64 
  lib64kwin4_effect_builtins1    5.20.4       1.mga8        x86_64 
  lib64kwin5                     5.20.4       1.mga8        x86_64 
  lib64kwineffects12             5.20.4       1.mga8        x86_64 
  lib64kwinglutils12             5.20.4       1.mga8        x86_64 
  lib64kwinxrenderutils12        5.20.4       1.mga8        x86_64 
  lib64kworkspace5               5.20.4       1.mga8        x86_64 
  lib64lsofui9                   5.20.4       1.mga8        x86_64 
  lib64milou5                    5.20.4       1.mga8        x86_64 
  lib64notificationmanager1      5.20.4       1.mga8        x86_64 
  lib64oxygenstyle5_5            5.20.4       1.mga8        x86_64 
  lib64oxygenstyleconfig5_5      5.20.4       1.mga8        x86_64 
  lib64phabricatorhelpers5       5.76.0       1.mga8        x86_64 
  lib64plasma-geolocation-inter> 5.20.4       1.mga8        x86_64 
  lib64plasmacomicprovidercore1  5.20.4       1.mga8        x86_64 
  lib64plasmapotdprovidercore1   5.20.4       1.mga8        x86_64 
  lib64powerdevilconfigcommonpr> 5.20.4       1.mga8        x86_64 
  lib64powerdevilcore2           5.20.4       1.mga8        x86_64 
  lib64powerdevilui5             5.20.4       1.mga8        x86_64 
  lib64processcore9              5.20.4       1.mga8        x86_64 
  lib64processui9                5.20.4       1.mga8        x86_64 
  lib64qt5-database-plugin-ibase 5.15.2       1.mga8        x86_64 
  lib64qt5-database-plugin-mysql 5.15.2       1.mga8        x86_64 
  lib64qt5-database-plugin-odbc  5.15.2       1.mga8        x86_64 
  lib64qt5-database-plugin-pgsql 5.15.2       1.mga8        x86_64 
  lib64qt5-database-plugin-sqli> 5.15.2       1.mga8        x86_64 
  lib64qt5-database-plugin-tds   5.15.2       1.mga8        x86_64 
  lib64qt5base5-devel            5.15.2       1.mga8        x86_64 
  lib64qt5charts5                5.15.2       1.mga8        x86_64 
  lib64qt5concurrent-devel       5.15.2       1.mga8        x86_64 
  lib64qt5concurrent5            5.15.2       1.mga8        x86_64 
  lib64qt5core-devel             5.15.2       1.mga8        x86_64 
  lib64qt5core5                  5.15.2       1.mga8        x86_64 
  lib64qt5dbus-devel             5.15.2       1.mga8        x86_64 
  lib64qt5dbus5                  5.15.2       1.mga8        x86_64 
  lib64qt5designer5              5.15.2       2.mga8        x86_64 
  lib64qt5eglfsdeviceintegratio> 5.15.2       1.mga8        x86_64 
  lib64qt5eglfsdeviceintegratio> 5.15.2       1.mga8        x86_64 
  lib64qt5eglfskmssupport-devel  5.15.2       1.mga8        x86_64 
  lib64qt5eglfskmssupport5       5.15.2       1.mga8        x86_64 
  lib64qt5gui-devel              5.15.2       1.mga8        x86_64 
  lib64qt5gui5                   5.15.2       1.mga8        x86_64 
  lib64qt5help5                  5.15.2       2.mga8        x86_64 
  lib64qt5multimedia5            5.15.2       1.mga8        x86_64 
  lib64qt5multimediagsttools5    5.15.2       1.mga8        x86_64 
  lib64qt5multimediaquick5       5.15.2       1.mga8        x86_64 
  lib64qt5multimediawidgets5     5.15.2       1.mga8        x86_64 
  lib64qt5network-devel          5.15.2       1.mga8        x86_64 
  lib64qt5network5               5.15.2       1.mga8        x86_64 
  lib64qt5networkauth5           5.15.2       1.mga8        x86_64 
  lib64qt5opengl-devel           5.15.2       1.mga8        x86_64 
  lib64qt5opengl5                5.15.2       1.mga8        x86_64 
  lib64qt5pdf5                   5.15.2       2.mga8        x86_64 
  lib64qt5positioning5           5.15.2       1.mga8        x86_64 
  lib64qt5printsupport-devel     5.15.2       1.mga8        x86_64 
  lib64qt5printsupport5          5.15.2       1.mga8        x86_64 
  lib64qt5qml-devel              5.15.2       1.mga8        x86_64 
  lib64qt5qml5                   5.15.2       1.mga8        x86_64 
  lib64qt5qmlmodels-devel        5.15.2       1.mga8        x86_64 
  lib64qt5qmlmodels5             5.15.2       1.mga8        x86_64 
  lib64qt5qmlworkerscript5       5.15.2       1.mga8        x86_64 
  lib64qt5quick-devel            5.15.2       1.mga8        x86_64 
  lib64qt5quick5                 5.15.2       1.mga8        x86_64 
  lib64qt5quickcontrols2_5       5.15.2       1.mga8        x86_64 
  lib64qt5quickparticles5        5.15.2       1.mga8        x86_64 
  lib64qt5quickshapes5           5.15.2       1.mga8        x86_64 
  lib64qt5quicktemplates2_5      5.15.2       1.mga8        x86_64 
  lib64qt5quicktest-devel        5.15.2       1.mga8        x86_64 
  lib64qt5quicktest5             5.15.2       1.mga8        x86_64 
  lib64qt5quickwidgets5          5.15.2       1.mga8        x86_64 
  lib64qt5script5                5.15.2       1.mga8        x86_64 
  lib64qt5sensors5               5.15.2       1.mga8        x86_64 
  lib64qt5serialport5            5.15.2       1.mga8        x86_64 
  lib64qt5sql-devel              5.15.2       1.mga8        x86_64 
  lib64qt5sql5                   5.15.2       1.mga8        x86_64 
  lib64qt5svg5                   5.15.2       1.mga8        x86_64 
  lib64qt5test-devel             5.15.2       1.mga8        x86_64 
  lib64qt5test5                  5.15.2       1.mga8        x86_64 
  lib64qt5texttospeech5          5.15.2       1.mga8        x86_64 
  lib64qt5waylandclient5         5.15.2       1.mga8        x86_64 
  lib64qt5waylandcompositor5     5.15.2       1.mga8        x86_64 
  lib64qt5webchannel5            5.15.2       1.mga8        x86_64 
  lib64qt5webengine5             5.15.2       2.mga8        x86_64 
  lib64qt5webenginecore5         5.15.2       2.mga8        x86_64 
  lib64qt5webenginewidgets5      5.15.2       2.mga8        x86_64 
  lib64qt5webkit5                5.212.0      1.alpha4.6.m> x86_64 
  lib64qt5webkitwidgets5         5.212.0      1.alpha4.6.m> x86_64 
  lib64qt5widgets-devel          5.15.2       1.mga8        x86_64 
  lib64qt5widgets5               5.15.2       1.mga8        x86_64 
  lib64qt5x11extras5             5.15.2       1.mga8        x86_64 
  lib64qt5xcbqpa-devel           5.15.2       1.mga8        x86_64 
  lib64qt5xcbqpa5                5.15.2       1.mga8        x86_64 
  lib64qt5xml-devel              5.15.2       1.mga8        x86_64 
  lib64qt5xml5                   5.15.2       1.mga8        x86_64 
  lib64qt5xmlpatterns5           5.15.2       1.mga8        x86_64 
  lib64re2_9                     20201101     2.mga8        x86_64 
  lib64reviewboardhelpers5       5.76.0       1.mga8        x86_64 
  lib64sdl2_mixer2.0_0           2.0.4        3.mga8        x86_64 
  lib64sdl2_ttf2.0_0             2.0.15       2.mga8        x86_64 
  lib64systemsettingsview3       5.20.4       1.mga8        x86_64 
  lib64taskmanager6              5.20.4       1.mga8        x86_64 
  lib64unbound8                  1.13.0       1.mga8        x86_64 
  lib64weather_ion7              5.20.4       1.mga8        x86_64 
  libgcc1                        10.2.1       0.20201205.1> x86_64 
  libgfortran5                   10.2.1       0.20201205.1> x86_64 
  libgomp-devel                  10.2.1       0.20201205.1> x86_64 
  libgomp1                       10.2.1       0.20201205.1> x86_64 
  libkscreen                     5.20.4       1.mga8        x86_64 
  libksysguard                   5.20.4       1.mga8        x86_64 
  libobjc4                       10.2.1       0.20201205.1> x86_64 
  libquadmath0                   10.2.1       0.20201205.1> x86_64 
  libstdc++-devel                10.2.1       0.20201205.1> x86_64 
  libstdc++-python-devel         10.2.1       0.20201205.1> x86_64 
  libstdc++-static-devel         10.2.1       0.20201205.1> x86_64 
  libstdc++6                     10.2.1       0.20201205.1> x86_64 
  mageia-release-Default         8            0.17.mga8     x86_64 
  mageia-release-common          8            0.17.mga8     x86_64 
  milou                          5.20.4       1.mga8        x86_64 
  networkmanager-qt              5.76.0       1.mga8        x86_64 
  oxygen                         5.20.4       1.mga8        x86_64 
  oxygen-icons5                  5.76.0       1.mga8        noarch 
  oxygen-sounds                  5.20.4       1.mga8        noarch 
  plasma-browser-integration     5.20.4       1.mga8        x86_64 
  plasma-desktop                 5.20.4       1.mga8        x86_64 
  plasma-framework               5.76.0       1.mga8        x86_64 
  plasma-integration             5.20.4       1.mga8        x86_64 
  plasma-pa                      5.20.4       1.mga8        x86_64 
  plasma-workspace               5.20.4       1.mga8        x86_64 
  polkit-kde-agent-1             5.20.4       1.mga8        x86_64 
  powerdevil                     5.20.4       1.mga8        x86_64 
  prison                         5.76.0       1.mga8        x86_64 
  purpose                        5.76.0       1.mga8        x86_64 
  python3-pygame                 2.0.0        1.mga8        x86_64 
  python3-qt5-core               5.15.2       1.mga8        x86_64 
  python3-qt5-dbus               5.15.2       1.mga8        x86_64 
  python3-qt5-gui                5.15.2       1.mga8        x86_64 
  python3-qt5-network            5.15.2       1.mga8        x86_64 
  python3-qt5-printsupport       5.15.2       1.mga8        x86_64 
  python3-qt5-qml                5.15.2       1.mga8        x86_64 
  python3-qt5-quick              5.15.2       1.mga8        x86_64 
  python3-qt5-svg                5.15.2       1.mga8        x86_64 
  python3-qt5-webchannel         5.15.2       1.mga8        x86_64 
  python3-qt5-webenginecore      5.15.2       1.mga8        x86_64 
  python3-qt5-webenginewidgets   5.15.2       1.mga8        x86_64 
  python3-qt5-webkit             5.15.2       1.mga8        x86_64 
  python3-qt5-webkitwidgets      5.15.2       1.mga8        x86_64 
  python3-qt5-widgets            5.15.2       1.mga8        x86_64 
  python3-qt5-xml                5.15.2       1.mga8        x86_64 
  python3-unbound                1.13.0       1.mga8        x86_64 
  qqc2-desktop-style             5.76.0       1.mga8        x86_64 
  qt-creator                     4.13.3       1.mga8        x86_64 
  qt-creator-doc                 4.13.3       1.mga8        noarch 
  qtbase5-common                 5.15.2       1.mga8        x86_64 
  qtbase5-common-devel           5.15.2       1.mga8        x86_64 
  qtcharts5                      5.15.2       1.mga8        x86_64 
  qtdeclarative5                 5.15.2       1.mga8        x86_64 
  qtgraphicaleffects5            5.15.2       1.mga8        x86_64 
  qtimageformats5                5.15.2       1.mga8        x86_64 
  qtmultimedia5                  5.15.2       1.mga8        x86_64 
  qtquickcontrols25              5.15.2       1.mga8        x86_64 
  qtquickcontrols5               5.15.2       1.mga8        x86_64 
  qtsensors5                     5.15.2       1.mga8        x86_64 
  qtspeech5                      5.15.2       1.mga8        x86_64 
  qtsvg5                         5.15.2       1.mga8        x86_64 
  qttools5                       5.15.2       2.mga8        x86_64 
  qttools5-assistant             5.15.2       2.mga8        x86_64 
  qttools5-designer              5.15.2       2.mga8        x86_64 
  qttools5-qtdbus                5.15.2       2.mga8        x86_64 
  qttools5-qtpaths               5.15.2       2.mga8        x86_64 
  qttranslations5                5.15.2       1.mga8        noarch 
  qtwayland5                     5.15.2       1.mga8        x86_64 
  qtwebengine5                   5.15.2       2.mga8        x86_64 
  qtxmlpatterns5-xmlpatterns     5.15.2       1.mga8        x86_64 
  sddm-kcm                       5.20.4       1.mga8        x86_64 
  simple-scan                    3.38.2       1.mga8        x86_64 
  solid                          5.76.0       1.mga8        x86_64 
  sonnet                         5.76.0       1.mga8        x86_64 
  syntax-highlighting            5.76.0       1.mga8        x86_64 
  systemsettings                 5.20.4       1.mga8        x86_64 
  wine64                         6.0          1.rc1.1.mga8  x86_64 
299MB of additional disk space will be used.
439MB of packages will be retrieved.


I thought that maybe the compositor had been inadvertently disabled, so I brought up the Compositor configuration and saw the warning shown in the image.

PlasmaCompositorSettings.png
PlasmaCompositorSettings.png (98.51 KiB) Viewed 724 times


The compositor is enabled.

I'm not sure if that is an exceptional warning message or a warning that just shows up all the time.

According to inxi, nvidia is doing the rendering.

Code: Select all
[poobah@localhost ~]$ inxi -b
System:    Host: localhost Kernel: 5.10.4-desktop-1.mga8 x86_64 bits: 64 Desktop: KDE Plasma 5.20.4 Distro: Mageia 8 mga8
Machine:   Type: Desktop Mobo: ASUSTeK model: P5G41T-M LX PLUS v: Rev X.0x serial: <superuser required>
           BIOS: American Megatrends v: 0502 date: 10/21/2011
CPU:       Info: Dual Core Intel Core2 Duo E7300 [MCP] speed: 2210 MHz
Graphics:  Device-1: NVIDIA G94 [GeForce 9600 GT] driver: nvidia v: 340.108
           Display: x11 server: Mageia X.org 1.20.10 driver: nvidia,v4l resolution: 1920x1080~60Hz
           OpenGL: renderer: GeForce 9600 GT/PCIe/SSE2 v: 3.3.0 NVIDIA 340.108


I also do not know what version of OpenGL I should select. It looks like the renderer is v 3.3.0. The compositor is using 2.0. The other options are XRender and 3.1.

Any pointers to where I can study these issues would be welcome.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby doktor5000 » Jan 1st, '21, 00:28

Could either be the Qt update, or maybe your OpenGL stack is somehow borked.

If you select Xrender for the render backend, does that make a difference ?
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Jan 1st, '21, 01:46

Yep. I set the back end to XRender and the transparency works again.

I think I will set it to OpenGL 3.1 to see what that does. I have read that there have been problems with that back end, hence it defaults to OpenGL 2.0.

Edit:
I set the back end to OpenGL3.1 and the transparency failed again. So I guess my OpenGL stack is, in fact, somehow borked. It is now back on XRender.

I will have to go study what all this means.
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Re: Transparent backgrounds are opaque black on Mageia 8

Postby banjo » Jan 1st, '21, 02:24

I am going to mark this SOLVED since the transparency is working again even though I don't understand what has gone wrong with the OpenGL backend.

The workaround is

System Settings => Display and Monitor => Compositor

Then, for the Rendering backend: select XRender.
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Re: [SOLVED]Transparent backgrounds are opaque black on Mage

Postby banjo » Jan 3rd, '21, 00:30

There is another way to fix this problem that I just figured out.

Somehow, the Compositor has locked out parts of OpenGL in the backend, and that causes the translucency to stop working.... even though it still allows you to select OpenGL as the backend.

When I opened System Settings => Display and Monitor => Compositor, the dialog has a dire warning about the display driver and OpenGL as shown in the screenshot below:

CompositorOPenGLWarning.png
CompositorOPenGLWarning.png (104.16 KiB) Viewed 691 times


The warning says:

"OpenGL compositing (the default) has crashed KWin in the past.
This was most likely due to a driver bug.
If you think that you have meanwhile upgraded to a stable driver,
you can reset this protection but be aware that this might result in an immediate crash!
Alternatively, you might want to use the Xrender backend instead."

Then there is a button at the bottom that says

"Re-enable OpenGl detection" and a red X next to it.

I held my breath and clicked on the button to reset the interlock, and the warning went away. I re-applied the OpenGL backend and the transparency came back.

I do not know what the red X does.

So this is also a possible fix for this problem.... or for an immediate crash.
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