Revit二次开发，写一个类似于public static RibbonPanel CreateButton<T>(this RibbonPanel panel, Action<PushButtonData> action) { if (panel == null) { throw new ArgumentNullException(nameof(panel), "panel can not be null"); } if (action == null) { throw new ArgumentNullException(nameof(action), "action can not be null"); } Type commandType = typeof(T); string name = $"btn_{commandType.Name}"; PushButtonData pushButtonData = new PushButtonData(name, name, commandType.Assembly.Location, commandType.FullName); action.Invoke(pushButtonData); panel.AddItem(pushButtonData); return panel; }这样的拓展方法来添加层叠按钮，三个小按钮上中下排列

好的，我可以给你提供一个示例代码，实现在Revit中创建一个层叠的RibbonPanel并添加三个按钮，分别排列在上、中、下三个位置。

首先，你需要在Revit二次开发环境中创建一个类，包含一个静态方法来实现添加三个按钮的功能。代码如下：

public static class RibbonExtensions
{
    public static RibbonPanel CreateStackedButtons(this RibbonTab tab, string panelName, string panelTitle, string upButtonName, string midButtonName, string downButtonName)
    {
        // Create a new panel
        RibbonPanel panel = tab.GetPanel(panelName);
        if (panel == null)
        {
            panel = tab.AddItem(new RibbonPanel(panelName, panelTitle));
        }

        // Create three push buttons
        PushButtonData upButtonData = new PushButtonData(upButtonName, "Up", Assembly.GetExecutingAssembly().Location, typeof(UpCommand).FullName);
        PushButtonData midButtonData = new PushButtonData(midButtonName, "Mid", Assembly.GetExecutingAssembly().Location, typeof(MidCommand).FullName);
        PushButtonData downButtonData = new PushButtonData(downButtonName, "Down", Assembly.GetExecutingAssembly().Location, typeof(DownCommand).FullName);

        // Add the buttons to the panel
        panel.AddItem(upButtonData);
        panel.AddItem(midButtonData);
        panel.AddItem(downButtonData);

        // Set the layout of the buttons
        int nItems = panel.GetItems().Count;
        panel.SetItemPlacement(nItems - 3, RibbonItemPlacement.Large);
        panel.SetItemPlacement(nItems - 2, RibbonItemPlacement.Medium);
        panel.SetItemPlacement(nItems - 1, RibbonItemPlacement.Small);

        return panel;
    }
}

在上面的代码中，我们使用了Revit API中的RibbonPanel和PushButtonData类来创建一个层叠的RibbonPanel，并添加三个按钮。同时，我们还使用了RibbonItemPlacement枚举来设置按钮的排列位置。

接下来，你需要创建三个命令类（UpCommand、MidCommand和DownCommand），分别继承自IExternalCommand接口，并实现Execute方法来实现按钮的具体功能。代码示例如下：

[Transaction(TransactionMode.Manual)]
public class UpCommand : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
    {
        // TODO: Add your command code here

        return Result.Succeeded;
    }
}

[Transaction(TransactionMode.Manual)]
public class MidCommand : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
    {
        // TODO: Add your command code here

        return Result.Succeeded;
    }
}

[Transaction(TransactionMode.Manual)]
public class DownCommand : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
    {
        // TODO: Add your command code here

        return Result.Succeeded;
    }
}

最后，在你的插件启动代码中，你可以调用上面定义的RibbonExtensions.CreateStackedButtons方法来创建层叠的RibbonPanel，并添加三个按钮。示例代码如下：

public Result OnStartup(UIControlledApplication application)
{
    // Get the current ribbon tab
    RibbonTab tab = application.CreateRibbonTab("MyTab");

    // Create a stacked button panel
    RibbonPanel panel = tab.CreateStackedButtons("MyPanel", "My Panel", "UpButton", "MidButton", "DownButton");

    return Result.Succeeded;
}

运行你的插件，你将会在Revit的Ribbon菜单中看到一个新的选项卡，其中包含一个层叠的RibbonPanel，并添加了三个按钮。这三个按钮分别排列在上、中、下三个位置。