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.

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 }}

}