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Forum Update on Monday, May 27th 2025

Qt6 platform rendering issues on Ubuntu 22.04

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  • JoeCFDJ JoeCFD

    @Robert-Hairgrove I guess the problem should be gone if you switch to X11. Do you have to use Wayland? Wayland is the default setting in Ubuntu 22.04.

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    Robert Hairgrove
    wrote on last edited by
    #17

    @JoeCFD "X11" is not listed as an available platform argument (see my reply to @SGaist above).

    How would I do this, switch to X11?

    JoeCFDJ 1 Reply Last reply
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    • R Robert Hairgrove

      @JoeCFD "X11" is not listed as an available platform argument (see my reply to @SGaist above).

      How would I do this, switch to X11?

      JoeCFDJ Offline
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      JoeCFD
      wrote on last edited by JoeCFD
      #18

      @Robert-Hairgrove logout your account. You can see a settings icon on the login screen and click the setting icon to select Xorg. Then log in and you will be good.

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      • JoeCFDJ JoeCFD

        @Robert-Hairgrove logout your account. You can see a settings icon on the login screen and click the setting icon to select Xorg. Then log in and you will be good.

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        Robert Hairgrove
        wrote on last edited by
        #19

        @JoeCFD Thanks.

        I logged in again with XOrg, but unfortunately the problem persists.

        JoeCFDJ 1 Reply Last reply
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        • JoeCFDJ JoeCFD

          @Robert-Hairgrove logout your account. You can see a settings icon on the login screen and click the setting icon to select Xorg. Then log in and you will be good.

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          Robert Hairgrove
          wrote on last edited by
          #20

          @JoeCFD BTW, what is "LXQt"?

          JoeCFDJ 1 Reply Last reply
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          • R Robert Hairgrove

            @JoeCFD Thanks.

            I logged in again with XOrg, but unfortunately the problem persists.

            JoeCFDJ Offline
            JoeCFDJ Offline
            JoeCFD
            wrote on last edited by
            #21

            @Robert-Hairgrove did you do:
            make distclean
            qmake
            make
            run

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            • R Robert Hairgrove

              @JoeCFD BTW, what is "LXQt"?

              JoeCFDJ Offline
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              JoeCFD
              wrote on last edited by
              #22

              @Robert-Hairgrove said in Qt6 platform rendering issues on Ubuntu 22.04:

              LXQt

              https://lxqt-project.org/

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              • R Offline
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                Robert Hairgrove
                wrote on last edited by
                #23

                OK, this must be a bug introduced in 6.5.

                I installed Qt versions 6.2.4, 6.3.2, 6.4.3 in addition to 6.5.3 and 6.6.0. Up to 6.4.3, the controls are displayed correctly (enabled=black text, disabled=gray).

                Beginning with 6.5.3 and also 6.6.0, the problem arises (everything displays as if enabled, regardless of state).

                Looks like I need to file a bug report, but I don't have time today to do it today.

                JonBJ SGaistS JoeCFDJ 3 Replies Last reply
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                • R Robert Hairgrove

                  OK, this must be a bug introduced in 6.5.

                  I installed Qt versions 6.2.4, 6.3.2, 6.4.3 in addition to 6.5.3 and 6.6.0. Up to 6.4.3, the controls are displayed correctly (enabled=black text, disabled=gray).

                  Beginning with 6.5.3 and also 6.6.0, the problem arises (everything displays as if enabled, regardless of state).

                  Looks like I need to file a bug report, but I don't have time today to do it today.

                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by
                  #24

                  @Robert-Hairgrove
                  As before, this is only a suggestion. I wonder whether Qt 6.5+ has introduced some change in default so that it is using Wayland over Xorg? And that might be the cause of the changed look? I came across e.g. Qt 6.5 Adding Wayland Native Interface

                  and now set to come with Qt 6.5 is support for a Wayland native interface for application developers wanting to interact directly with Wayland object handles.

                  Did Qt 6.5 become more preferentially Wayland-y than earlier?

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                  • JonBJ JonB

                    @Robert-Hairgrove
                    As before, this is only a suggestion. I wonder whether Qt 6.5+ has introduced some change in default so that it is using Wayland over Xorg? And that might be the cause of the changed look? I came across e.g. Qt 6.5 Adding Wayland Native Interface

                    and now set to come with Qt 6.5 is support for a Wayland native interface for application developers wanting to interact directly with Wayland object handles.

                    Did Qt 6.5 become more preferentially Wayland-y than earlier?

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                    Robert Hairgrove
                    wrote on last edited by
                    #25

                    @JonB I get the same result regardless of whether I log in using Xorg or Wayland, as far as the enabled/disabled bug is concerned.

                    If I log in with Xorg, Qt seems to load xcb, otherwise wayland is used. I can also specify either platform on the command line; this will change the way some things are displayed, e.g. window border or not, but in every case the bug described above still persists.

                    BTW I also made sure that the Qt Wayland Compositor module was included in all of the installations of Qt. I thought not having that installed might have led to the error, but apparently it makes no difference.

                    JonBJ 1 Reply Last reply
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                    • R Robert Hairgrove

                      @JonB I get the same result regardless of whether I log in using Xorg or Wayland, as far as the enabled/disabled bug is concerned.

                      If I log in with Xorg, Qt seems to load xcb, otherwise wayland is used. I can also specify either platform on the command line; this will change the way some things are displayed, e.g. window border or not, but in every case the bug described above still persists.

                      BTW I also made sure that the Qt Wayland Compositor module was included in all of the installations of Qt. I thought not having that installed might have led to the error, but apparently it makes no difference.

                      JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by
                      #26

                      @Robert-Hairgrove said in Qt6 platform rendering issues on Ubuntu 22.04:

                      this will change the way some things are displayed, e.g. window border or not, but in every case the bug described above still persists.

                      Ah. So it does make a difference as I suspected, but it does not resolve/alter your particular issue.

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                      • R Robert Hairgrove

                        OK, this must be a bug introduced in 6.5.

                        I installed Qt versions 6.2.4, 6.3.2, 6.4.3 in addition to 6.5.3 and 6.6.0. Up to 6.4.3, the controls are displayed correctly (enabled=black text, disabled=gray).

                        Beginning with 6.5.3 and also 6.6.0, the problem arises (everything displays as if enabled, regardless of state).

                        Looks like I need to file a bug report, but I don't have time today to do it today.

                        SGaistS Offline
                        SGaistS Offline
                        SGaist
                        Lifetime Qt Champion
                        wrote on last edited by
                        #27

                        @Robert-Hairgrove said in Qt6 platform rendering issues on Ubuntu 22.04:

                        OK, this must be a bug introduced in 6.5.

                        I installed Qt versions 6.2.4, 6.3.2, 6.4.3 in addition to 6.5.3 and 6.6.0. Up to 6.4.3, the controls are displayed correctly (enabled=black text, disabled=gray).

                        Beginning with 6.5.3 and also 6.6.0, the problem arises (everything displays as if enabled, regardless of state).

                        Looks like I need to file a bug report, but I don't have time today to do it today.

                        Looks like you may have found a regression, you should check the bug report system.

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                        • R Robert Hairgrove

                          OK, this must be a bug introduced in 6.5.

                          I installed Qt versions 6.2.4, 6.3.2, 6.4.3 in addition to 6.5.3 and 6.6.0. Up to 6.4.3, the controls are displayed correctly (enabled=black text, disabled=gray).

                          Beginning with 6.5.3 and also 6.6.0, the problem arises (everything displays as if enabled, regardless of state).

                          Looks like I need to file a bug report, but I don't have time today to do it today.

                          JoeCFDJ Offline
                          JoeCFDJ Offline
                          JoeCFD
                          wrote on last edited by JoeCFD
                          #28

                          @Robert-Hairgrove I just installed 6.6.0 in Lubuntu 22.04 and my test case runs fine. QLabel is greyed out when it is disabled.

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                          • JoeCFDJ JoeCFD

                            @Robert-Hairgrove I just installed 6.6.0 in Lubuntu 22.04 and my test case runs fine. QLabel is greyed out when it is disabled.

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                            Robert Hairgrove
                            wrote on last edited by
                            #29

                            @JoeCFD I'm glad ... hiowever, I think Lubuntu is not the same as regular Ubuntu?

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                            • R Offline
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                              Robert Hairgrove
                              wrote on last edited by
                              #30

                              Bug report filed today:
                              https://bugreports.qt.io/browse/QTBUG-118468

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                              • R Offline
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                                Robert Hairgrove
                                wrote on last edited by
                                #31

                                The default application palette seems to be broken in places with Qt 6.5 and higher.

                                As a workaround, I serialized the working palette into a file using the testlabel app, compiling it with Qt 6.4.3. Then I added the resulting binary file to my application resources. When compiling it with a higher Qt version, I merely overwrite the default palette into the app instance.

                                Seems to work OK; now at least I can do some more serious testing.

                                1 Reply Last reply
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