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QMessageBox position and size are wrong

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  • JonBJ JonB

    There are many threads about Wayland controlling window positions instead of your program.

    K Offline
    K Offline
    kepeter
    wrote on last edited by
    #5

    @JonB
    I do not understand what are you suggesting... I do not control not size neither position. I left it to the default, which - to my understanding - should be centred...
    And if I have to write special code to deal with the underlying wayland layer, then what the point in QT?

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    • JonBJ Offline
      JonBJ Offline
      JonB
      wrote on last edited by JonB
      #6

      I am not suggesting anything.

      I was expecting - and remember that it was so - the message box to be centred on its parent and be correctly sized... But I got this...

      I asked whether you are running under Wayland. If so, Wayland will position the message box for you, and that may override the centering of a message box which perhaps used to happen under, say, Xorg, if that is what you used in the past.

      And if I have to write special code to deal with the underlying wayland layer, then what the point in QT?

      You don't have to write special code if it is a Wayland issue, and indeed it would be difficult to do so. Rather you accept that Wayland positions windows according to its rules. (Part of) The point of Qt is to provide a platform-independent layer for code including windowing functionality, not to somehow override or by-pass the native windowing system/manager.

      The first thing is to ascenrtain if you are running under Wayland. If you are not this is not relevant. If you are then try your code under Xorg and see if different behaviour?

      See also perhaps
      https://forum.qt.io/topic/157268/pyside6-the-move-method-cannot-move-the-specified-parameter-under-the-ubuntu22-04-system-how-should-this-problem-be-solved-so-that-it-can-be-centered-horizontally-and-vertically

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      • JonBJ JonB

        I am not suggesting anything.

        I was expecting - and remember that it was so - the message box to be centred on its parent and be correctly sized... But I got this...

        I asked whether you are running under Wayland. If so, Wayland will position the message box for you, and that may override the centering of a message box which perhaps used to happen under, say, Xorg, if that is what you used in the past.

        And if I have to write special code to deal with the underlying wayland layer, then what the point in QT?

        You don't have to write special code if it is a Wayland issue, and indeed it would be difficult to do so. Rather you accept that Wayland positions windows according to its rules. (Part of) The point of Qt is to provide a platform-independent layer for code including windowing functionality, not to somehow override or by-pass the native windowing system/manager.

        The first thing is to ascenrtain if you are running under Wayland. If you are not this is not relevant. If you are then try your code under Xorg and see if different behaviour?

        See also perhaps
        https://forum.qt.io/topic/157268/pyside6-the-move-method-cannot-move-the-specified-parameter-under-the-ubuntu22-04-system-how-should-this-problem-be-solved-so-that-it-can-be-centered-horizontally-and-vertically

        K Offline
        K Offline
        kepeter
        wrote on last edited by
        #7

        @JonB

        Thank you for the explanation - now I see what you was saying...
        I was under the impression - based on what I saw in the documentation - that the modal shuld be automatically centred by QT, regardless of the underlying technology...
        Displays a simple message box about Qt, with the given title and centered over parent (if parent is not nullptr).
        Not aboutQt neither question does it...

        I will try what called 'property-based API' in the documentation to solve the problem...

        Thank you

        JonBJ 1 Reply Last reply
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        • K kepeter

          @JonB

          Thank you for the explanation - now I see what you was saying...
          I was under the impression - based on what I saw in the documentation - that the modal shuld be automatically centred by QT, regardless of the underlying technology...
          Displays a simple message box about Qt, with the given title and centered over parent (if parent is not nullptr).
          Not aboutQt neither question does it...

          I will try what called 'property-based API' in the documentation to solve the problem...

          Thank you

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by
          #8

          @kepeter
          I agree about that doc quote, but I am not sure whether it does not apply under Wayland. You still have not stated whether you are running under Wayland. If you are, and that is the reason, there is nothing for you to do about it. I don't know about a "property-based API'". Leave it to you to find out if you are under Wayland and this is a Wayland behaviour.

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          • JonBJ JonB

            @kepeter
            I agree about that doc quote, but I am not sure whether it does not apply under Wayland. You still have not stated whether you are running under Wayland. If you are, and that is the reason, there is nothing for you to do about it. I don't know about a "property-based API'". Leave it to you to find out if you are under Wayland and this is a Wayland behaviour.

            K Offline
            K Offline
            kepeter
            wrote on last edited by
            #9

            @JonB

            I missed your question about wayland (answered it earlier) - Fedora 39 uses wayland so I'm using it...

            I fiddled with the message box and found this:

            msg1 will center on the parent window, but will not show title bar

                QMessageBox msg1;
            
                msg1.setParent(this);
                msg1.setText("Are you sure?");
                msg1.setWindowTitle("Exit");
                msg1.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
                msg1.setDefaultButton(QMessageBox::No);
                msg1.setIcon(QMessageBox::Question);
                msg1.setWindowFlags(Qt::Popup);
            
                msg1.exec();
            

            9a85871c-c6a3-47f5-bcd1-c96612bc18bd-image.png

            msg2 will show title bar, but will not center

                QMessageBox msg2;
            
                msg2.setParent(this);
                msg2.setText("Are you sure?");
                msg2.setWindowTitle("Exit");
                msg2.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
                msg2.setDefaultButton(QMessageBox::No);
                msg2.setIcon(QMessageBox::Question);
                msg2.setWindowFlags(Qt::Dialog);
            
                msg2.exec();
            

            9810e3cc-c311-49e3-9aa1-de9703c340eb-image.png

            It seems some sort of bug - not sure where exactly, however I can be with the first option... So I will call it a day...

            Thank you...

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            • K kepeter

              I had this application on hold for a long time and when came back - on new OS install with latest QT 6 - I encountered a problem with QMessageBox...

              void AppWindow::closeEvent(QCloseEvent *event)
              {
                  if(QMessageBox::question(this, "Exit", "Are you sure?", QMessageBox::Yes | QMessageBox::No) == QMessageBox::Yes)
                  {
                      computer.requestInterruption();
                      computer.wait();
              
                      event->accept();
                  }
                  else
                  {
                      event->ignore();
                  }
              }
              

              I was expecting - and remember that it was so - the message box to be centred on its parent and be correctly sized... But I got this...
              f42cce59-85c2-4f7c-8e22-c9a9ca66095d-image.png

              As you can see the message box not centred and the size is incorrect, as the title not even shows...

              This is my environment:
              OS: Fedora 39
              QT: 6.6.2
              QT Creator: 10.0.2
              Compiler: gcc 13.3.1

              While everything functioning perfectly I would like it to be also pleasing to the eye...

              A Offline
              A Offline
              anil_arise
              wrote on last edited by
              #10

              @kepeter

              You can use move as per designated co-ordinates

              Example:
              msg1.move(this->width()/2,this->height()/2)

              Christian EhrlicherC 1 Reply Last reply
              0
              • A anil_arise

                @kepeter

                You can use move as per designated co-ordinates

                Example:
                msg1.move(this->width()/2,this->height()/2)

                Christian EhrlicherC Offline
                Christian EhrlicherC Offline
                Christian Ehrlicher
                Lifetime Qt Champion
                wrote on last edited by
                #11

                @anil_arise Wayland does not allow moving top level widgets. Otherwise the OP would not have such problems...

                Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
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                • Christian EhrlicherC Christian Ehrlicher

                  @anil_arise Wayland does not allow moving top level widgets. Otherwise the OP would not have such problems...

                  K Offline
                  K Offline
                  kepeter
                  wrote on last edited by
                  #12

                  @Christian-Ehrlicher
                  These are NOT top-level... Every and each has a parent...

                  JonBJ 1 Reply Last reply
                  0
                  • K kepeter

                    @Christian-Ehrlicher
                    These are NOT top-level... Every and each has a parent...

                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by
                    #13

                    @kepeter said in QMessageBox position and size are wrong:

                    These are NOT top-level... Every and each has a parent...

                    It is top-level. Read https://doc.qt.io/qt-6/qdialog.html#QDialog

                    Constructs a dialog with parent parent.

                    A dialog is always a top-level widget, but if it has a parent, its default location is centered on top of the parent

                    Dialogs only use parent for positioning. And we believe Wayland ignores/does not allow that.

                    K 1 Reply Last reply
                    1
                    • JonBJ JonB

                      @kepeter said in QMessageBox position and size are wrong:

                      These are NOT top-level... Every and each has a parent...

                      It is top-level. Read https://doc.qt.io/qt-6/qdialog.html#QDialog

                      Constructs a dialog with parent parent.

                      A dialog is always a top-level widget, but if it has a parent, its default location is centered on top of the parent

                      Dialogs only use parent for positioning. And we believe Wayland ignores/does not allow that.

                      K Offline
                      K Offline
                      kepeter
                      wrote on last edited by
                      #14

                      @JonB

                      It sounds me like an implementation issue of Qt against wayland... It is clear that there is no problem to center a child dialog - every gnome application does it...

                      Thank you

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                      • Christian EhrlicherC Offline
                        Christian EhrlicherC Offline
                        Christian Ehrlicher
                        Lifetime Qt Champion
                        wrote on last edited by Christian Ehrlicher
                        #15

                        It's not a child dialog but a top level widget. Child dialogs are properly centered as you can see in the testcase above.

                        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                        Visit the Qt Academy at https://academy.qt.io/catalog

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