隐藏WPF中的列后，将清除DataGridTemplateColumn中的ComboBox

<DataGridTemplateColumn Header="Column1" Visibility="{Binding IsColumnVisible}">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <ComboBox SelectedItem="{Binding ComboBoxValue}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

private object _comboBoxValue;
public object ComboBoxValue
{
    get { return _comboBoxValue; }
    set { _comboBoxValue = value; OnPropertyChanged(nameof(ComboBoxValue)); }
}

private bool _isColumnVisible;
public bool IsColumnVisible
{
    get { return _isColumnVisible; }
    set
    {
        if (!_isColumnVisible && value)
        {
            // 显示列时，将保存的ComboBox值赋值回去
            ComboBoxValue = SavedComboBoxValue;
        }
        else if (_isColumnVisible && !value)
        {
            // 隐藏列时，保存ComboBox的值
            SavedComboBoxValue = ComboBoxValue;
        }

        _isColumnVisible = value;
        OnPropertyChanged(nameof(IsColumnVisible));
    }
}