Let Controls inherit palettes and fonts from parents

The Item's palette property and Control's font property returns the
resolved value; its resolveMask is inherited from parent object, when
the return value is used in the qml. For example:

ApplicationWindow {
    id: window
    palette { window: "blue"; windowText: "blue" }

    Control {
        id: control
    }

    Button {
        onClicked: {
            control.palette.window = "red"
            window.palette.windowText = "red"
            console.log(control.palette.windowText)
        }
    }
}

In Button.onClicked, `control.palette` is the `resolvedPalette`
of Control, it's resolveMask is not 0. Next, the new value is assigned
to the control, then the control's "requestedPalette" will change to the
new value, and it's resolveMask also is not 0. Next,
`window.palette.windowText = "red"` changes the `windowText` palette for
the window; QQuickPaletteColorProvider::inheritPalette() will be called.
Because the resolveMask of `requestedPalette` is equal to the new
palette, the control will not inherit any colors from its parent. So
`console.log(control.palette.windowText)` was printing `qml: #0000ff`,
but the right result is `qml: #ff0000`.

When PaletteProvider is missing the inherited struct, fallbackPalette is
now used as parentPalette.

[ChangeLog][Controls] Controls now inherit palette and font from parents.

Done-With: Volker Hilsheimer <volker.hilsheimer@qt.io>
Done-With: yeshanshan <yeshanshan@uniontech.com>
Done-With: Shawn Rutledge <shawn.rutledge@qt.io>
Pick-to: 6.4
Fixes: QTBUG-101480
Change-Id: Ibe400f647512331352bf34dee42f908fb7a8d914
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Oliver Eftevaag <oliver.eftevaag@qt.io>

0 files changed, 0 insertions, 0 deletions