打開組合框（wpf）時ComboBoxItem綁定錯誤

Question

一旦使用combobox.isDropDownOpen獲得焦點，我就會打開組合框。我在控制台中收到以下綁定錯誤

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')

這是代碼：

private void combo_GotFocus(object sender, RoutedEventArgs e)
{
    placeholder.Visibility = Visibility.Collapsed;

    combo.IsDropDownOpen = true;
}

private void combo_LostFocus(object sender, RoutedEventArgs e)
{
    if (combo.Text.Equals(""))
    {
        placeholder.Visibility = Visibility.Visible;
    }

}

Answer 1

這些綁定錯誤是無害的。 請參考以下鏈接以獲取更多信息。

解決WPF中無害的綁定錯誤： https : //weblogs.asp.net/akjoshi/resolving-un-harmful-binding-errors-in-wpf