Fyne で個々の GUI コンポーネントの色をカスタマイズするにはどうすればよいですか?

<code class="go">type LabeledButton struct {
    Label     *fyne.Container
    Button    *fyne.Container
    Composited *fyne.CanvasObject
}

// NewLabeledButton creates a custom widget that combines a label and a button.
func NewLabeledButton(label, buttonText string) *LabeledButton {
    labelWidget := fyne.NewContainer(
        fyne.NewLabel(label),
        fyne.NewContainerWithLayout(labelLayout,
            fyne.NewContainer(fyne.NewSeparator())),
    )
    labelWidget.ExtendBaseWidget(labelWidget)

    buttonWidget := fyne.NewContainer(
        fyne.NewButton(buttonText, nil),
    )
    buttonWidget.ExtendBaseWidget(buttonWidget)

    composited := fyne.NewCanvasObject()
    composited.SetContent(fyne.NewVBox(labelWidget, buttonWidget))
    composited.Resize(labelWidget.MinSize().Add(buttonWidget.MinSize()))

    return &LabeledButton{
        Label:     labelWidget,
        Button:    buttonWidget,
        Composited: composited,
    }
}

// MinSize returns the minimum size required by the custom widget.
func (l *LabeledButton) MinSize() fyne.Size {
    return l.Composited.MinSize()
}

// Layout arranges the children of the custom widget.
func (l *LabeledButton) Layout(size fyne.Size) {
    l.Composited.Resize(size)
    l.Composited.Layout(size)
}

// Paint updates the display of the custom widget.
func (l *LabeledButton) Paint(w fyne.Window, c fyne.Canvas) {
    l.Composited.Paint(w, c)

    // Custom colors can be set here
    // (e.g., c.SetFillColor(color.NRGBA{R: 0, G: 255, B: 0, A: 255}))
}</code>