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Selection highlight is a thin blue bar at the left of the cell.

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  • S SimonSchroeder

    You data method only returns something for the few roles you have specified. Otherwise you are returning None. Try instead to return QAbstractItemModel.data(...) (I don't know Python and can't tell you how to exactly write that). This might solve your problem, but I'm not sure.

    SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote last edited by
    #6

    @SimonSchroeder said in Selection highlight is a thin blue bar at the left of the cell.:

    You data method only returns something for the few roles you have specified. Otherwise you are returning None. Try instead to return QAbstractItemModel.data(...) (I don't know Python and can't tell you how to exactly write that). This might solve your problem, but I'm not sure.

        return super().data(index, role)
    

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    • J Offline
      J Offline
      Jim G
      wrote last edited by
      #7

      In C++ you return a default QVariant() for default behavior. In PySide6 this maps to None, and QVariant is not even defined or available for use. Also, in PySide6 QAbstractItemModel.data() is virtual with no default implementation.

      Using return super().data(index,role) raises NotImplementedError as expected

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      • J Offline
        J Offline
        Jim G
        wrote last edited by Jim G
        #8

        OK, I think I found a bug. I closely examined some sample code I found that uses a QStandardItemModel, and displays selection highlights correctly. Here's a screenshot:

        2026-10-09_12-50-31.PNG

        Other than the change of model class, the only other difference I could find was that in the sample code there is this:

                # Alternating row colors for data density scannability
                self.table_view.setAlternatingRowColors(True)
        

        So I tried adding that to my code, and it fixed the issue:

        2026-10-09_12-53-11.PNG

        Bug?

        Also note that in my earlier screenshot showing the problem, there is already alternate row highlighting which is unexpected as the default for alternatingRowColors is False. Something's amiss here.

        Christian EhrlicherC 1 Reply Last reply
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        • J Jim G

          OK, I think I found a bug. I closely examined some sample code I found that uses a QStandardItemModel, and displays selection highlights correctly. Here's a screenshot:

          2026-10-09_12-50-31.PNG

          Other than the change of model class, the only other difference I could find was that in the sample code there is this:

                  # Alternating row colors for data density scannability
                  self.table_view.setAlternatingRowColors(True)
          

          So I tried adding that to my code, and it fixed the issue:

          2026-10-09_12-53-11.PNG

          Bug?

          Also note that in my earlier screenshot showing the problem, there is already alternate row highlighting which is unexpected as the default for alternatingRowColors is False. Something's amiss here.

          Christian EhrlicherC Online
          Christian EhrlicherC Online
          Christian Ehrlicher
          Lifetime Qt Champion
          wrote last edited by Christian Ehrlicher
          #9

          @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

          Bug?

          No, it's the default WinUI 3 style.

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          J 1 Reply Last reply
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          • Christian EhrlicherC Christian Ehrlicher

            @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

            Bug?

            No, it's the default WinUI 3 style.

            J Offline
            J Offline
            Jim G
            wrote last edited by
            #10

            @Christian-Ehrlicher said in Selection highlight is a thin blue bar at the left of the cell.:

            @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

            Bug?

            No, it's the default WinUI 3 style. Look into your explorer to see that the highlight is gray.

            I'm not following. I think we're talking about two different things. I can reproduce the issue using the sample code only.

            Here's the UI including self.table_view.setAlternatingRowColors(True) and line 4 selected:

            2026-10-09_12-50-31.PNG

            And now with that single line commented out and line 3 selected:

            2026-10-09_13-06-02.PNG

            Notice the "selection" highlight in the second screenshot is just a thin blue line at the left of each cell.

            It is unexpected that displaying the correct highlighting would involve the setting of alternatingRowColors.

            Christian EhrlicherC 1 Reply Last reply
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            • J Jim G

              @Christian-Ehrlicher said in Selection highlight is a thin blue bar at the left of the cell.:

              @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

              Bug?

              No, it's the default WinUI 3 style. Look into your explorer to see that the highlight is gray.

              I'm not following. I think we're talking about two different things. I can reproduce the issue using the sample code only.

              Here's the UI including self.table_view.setAlternatingRowColors(True) and line 4 selected:

              2026-10-09_12-50-31.PNG

              And now with that single line commented out and line 3 selected:

              2026-10-09_13-06-02.PNG

              Notice the "selection" highlight in the second screenshot is just a thin blue line at the left of each cell.

              It is unexpected that displaying the correct highlighting would involve the setting of alternatingRowColors.

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

              @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

              Notice the "selection" highlight in the second screenshot is just a thin blue line at the left of each cell.

              And that's the correct winui3 style.
              3d371abe-a5a4-4328-ae54-9f9e0395d0d7-grafik.png

              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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              • J Offline
                J Offline
                Jim G
                wrote last edited by Jim G
                #12

                So why does setting alternatingRowColors cause the change in highlight? Is that a bug?

                I'm not trying to be difficult. I'm still learning Qt/PySide6 (excellent tools IMO) and am puzzled by the need to set alternatingRowColors just to get the expected highlight behavior.

                Christian EhrlicherC S 2 Replies Last reply
                0
                • J Offline
                  J Offline
                  Jim G
                  wrote last edited by
                  #13

                  Also, what I see differs markedly from the example of winui 3 selection you cite. My selection indicators are only 2 pixels wide and jammed up against the left side of the text with no intervening space... actually they overlap (under) the leftmost pixel column of the text.

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                  • J Jim G

                    So why does setting alternatingRowColors cause the change in highlight? Is that a bug?

                    I'm not trying to be difficult. I'm still learning Qt/PySide6 (excellent tools IMO) and am puzzled by the need to set alternatingRowColors just to get the expected highlight behavior.

                    Christian EhrlicherC Online
                    Christian EhrlicherC Online
                    Christian Ehrlicher
                    Lifetime Qt Champion
                    wrote last edited by
                    #14

                    @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

                    So why does setting alternatingRowColors cause the change in highlight? Is that a bug?

                    The WinUI3 style has no information about alternating row colors so this is the solution for this.

                    med up against the left side of the text with no intervening space

                    This will be fixed

                    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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                    • J Jim G

                      So why does setting alternatingRowColors cause the change in highlight? Is that a bug?

                      I'm not trying to be difficult. I'm still learning Qt/PySide6 (excellent tools IMO) and am puzzled by the need to set alternatingRowColors just to get the expected highlight behavior.

                      S Offline
                      S Offline
                      SimonSchroeder
                      wrote last edited by
                      #15

                      @Jim-G said in Selection highlight is a thin blue bar at the left of the cell.:

                      So why does setting alternatingRowColors cause the change in highlight?

                      Qt tries to use the OS default widgets first. Alternating row colors is not supported by the OS directly. So, Qt will draw it from scratch and usually tries to mimic the OS look. Seems like it did not get updated, yet.

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