WPF 左键单击弹出菜单 ContextMenu

<Button x:Name="s" Content="Button" Click="s_Click">
            <Button.ContextMenu>
                <ContextMenu x:Name="menu">
                    <MenuItem x:Name="menu1" Header="菜单1"/>

　　　　　　　<Separator/>
                    <MenuItem x:Name="menu2" Header="菜单2">
                </ContextMenu>
            </Button.ContextMenu>
</Button>

        private void s_Click(object sender, RoutedEventArgs e)
        {
            this.menu.PlacementTarget = this.s;
            this.menu.IsOpen = true;
        }