我正在嘗試擴展 fyne 小部件以具有帶背景的簡單可點擊內容。我搜索了 fyne 小部件以找到一個可以用作入門的示例，并在 List/ListItem 中找到了類似的東西。我基本上復制了列表項代碼并稍微調整了一下。它看起來確實類似于fyne 文檔中的簡單示例。但是由于某些未知原因，go 給了我一個錯誤，我不知道原因是什么，也不知道如何解決：custom_widget/simple_card.go:80:24: c.card.super undefined (type *SimpleCard has no field or method super)這是模塊的代碼（custom_widget/simple_card.go）：package custom_widgetimport (    "fyne.io/fyne/v2"    "fyne.io/fyne/v2/canvas"    "fyne.io/fyne/v2/theme"    "fyne.io/fyne/v2/widget"    "log")// Declare conformity with interfaces.var _ fyne.Widget = (*SimpleCard)(nil)var _ fyne.Tappable = (*SimpleCard)(nil)type SimpleCard struct {    widget.BaseWidget    onTapped   func()    background *canvas.Rectangle    content    fyne.CanvasObject    selected   bool}func NewSimpleCard(content fyne.CanvasObject, tapped func()) *SimpleCard {    card := &SimpleCard{onTapped: tapped, content: content}    card.ExtendBaseWidget(card)    return card}// CreateRenderer is a private method to Fyne which links this custom_widget to its renderer.func (c *SimpleCard) CreateRenderer() fyne.WidgetRenderer {    c.ExtendBaseWidget(c)    c.background = canvas.NewRectangle(theme.SelectionColor())    c.background.Hide()    objects := []fyne.CanvasObject{c.background, c.content}    // NewBaseRenderer and BaseRenderer are copied from    // https://github.com/fyne-io/fyne/blob/master/internal/widget/base_renderer.go    // because the functionality is marked internal in fyne !?    return &SimpleCardRenderer{NewBaseRenderer(objects), c}}func (c *SimpleCard) Tapped(_ *fyne.PointEvent) {    log.Println("I have been tapped")    if c.onTapped != nil {        c.selected = true        c.Refresh()        c.onTapped()    }}// Declare conformity with the WidgetRenderer interface.var _ fyne.WidgetRenderer = (*SimpleCardRenderer)(nil)type SimpleCardRenderer struct {    BaseRenderer    card *SimpleCard}