C#源码实现隐藏在窗口左侧的工具栏小窗口，默认状态下，打开窗口时工具箱是隐藏的，可以只看到一条竖线，鼠标移到竖线上面，工具栏就展开了，展开的工具栏带关闭按钮，用户可在不需要时随时关闭它。 -C# source code to achieve the toolbar on the left side of the window a small window, the default, the toolbox is hidden when the window is opened, you can only see a vertical bar, mouse over the vertical line above the toolbar on the launching of the expanded Toolbar with Close button, the user can turn it off at any time when it is not needed.