Wpf PreviewDragOver PreviewDragEnter无法触发

适用环境：Windows 10 X64

修改注册表：

计算机HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionPoliciesSystemEnableLUA

的值为0

<TextBox Grid.Row="0" Grid.Column="0" AllowDrop="True" PreviewDragEnter="WhenPreviewDragOver" PreviewDragOver="WhenPreviewDragOver" Drop="WhenFileDrop" Background="Pink" Text="TextBox"></TextBox>

　

        private void WhenPreviewDragOver(object sender, DragEventArgs e)
        {
            e.Effects = DragDropEffects.All;
            e.Handled = true;
        }

        private void WhenFileDrop(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop, false))
            {
                string[] filePaths = e.Data.GetData(DataFormats.FileDrop) as string[];

                if (filePaths != null)
                {
                    MessageBox.Show(string.Join(Environment.NewLine, filePaths));
                }
            }
        }