WPF ContextMenu关闭当MenuItem有StackPanel时，如何保持它打开，即使在第一次点击？

<ToggleButton>
    <ToggleButton.Template>
        <ControlTemplate TargetType="ToggleButton">
            <ContentPresenter Content="{TemplateBinding Content}" />
        </ControlTemplate>
    </ToggleButton.Template>
    <ToggleButton.ContextMenu>
        <ContextMenu>
            <MenuItem Header="MenuItem 1">
                <StackPanel>
                    <!-- MenuItem内容 -->
                </StackPanel>
            </MenuItem>
        </ContextMenu>
    </ToggleButton.ContextMenu>
</ToggleButton>

public class CustomContextMenu : ContextMenu
{
    protected override void OnPreviewMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        // 取消关闭ContextMenu的默认行为
        e.Handled = true;
        base.OnPreviewMouseLeftButtonDown(e);
    }
}

// 应用自定义的ContextMenu
<Button>
    <Button.ContextMenu>
        <local:CustomContextMenu>
            <MenuItem Header="MenuItem 1">
                <StackPanel>
                    <!-- MenuItem内容 -->
                </StackPanel>
            </MenuItem>
        </local:CustomContextMenu>
    </Button.ContextMenu>
</Button>