QtQuick.Controls Button.qml wrong parent used for transitionDuration (line 77)

file:///C:/Qt/6.0.1/msvc2019_64/qml/QtQuick/Controls/Windows/Button.qml:77:49: Unable to assign [undefined] to int.

file:///C:/Qt/6.1.1/msvc2019_64/qml/QtQuick/Controls/Windows/Button.qml:77:49: Unable to assign [undefined] to int

Steps to reproduce the problem:

1. run the attached project
2. hover mouse cursor on top of the button

This warning comes up because in Button.qml at line 77 duration is set from the parent's transitionDuration, but the parent does not have one.

The warning is raised at runtime and happens if you hover over a button which does not set the transitionDuration manually before instantiating the object.

The parent at line 77 is Behaviour, but the intended parent is the Button in which the Behaviour is defined.

It should be either parent.parent.transitionDuration or an id can be set for the NativeStyle.Button which is used to guide to the intended parent and use that like so:

    NativeStyle.Button {
        id: exampleName
        control: control
        x: background.x
        y: background.y
        width: background.width
        height: background.height
        useNinePatchImage: false
        overrideState: NativeStyle.StyleItem.AlwaysHovered
        opacity: control.hovered ? 1 : 0

        Behavior on opacity {
            NumberAnimation { duration: exampleName.transitionDuration }
        }
    }