在花了相当长的时间查看源代码之后，除了扩展ControlCollection类并添加像“ClearStarts”和“ClearEnds”这样的事件之外，还有其他方法，这样您就可以忽略中间的以下删除操作，只对ClearEnds进行操作。

因此，我现在创建了自己的ControlCollection实现，并在FlowLayoutPanel实现中使用了它。Thx到专用方法Control.ControlCollection.CreateControlsInstance，实际上很容易“挂钩”，而不会对原始实现造成太多干扰：

public class ExtendedControlCollection : ControlCollection
{
    public event EventHandler OnBeforeClear;
    public event EventHandler OnAfterClear;

    public ExtendedControlCollection(Control owner) : base(owner)
    {
        
    }

    public override void Clear()
    {
        OnBeforeClear?.Invoke(this, new EventArgs());
        base.Clear();
        OnAfterClear?.Invoke(this, new EventArgs());
    }
}

以及我们FlowLayoutPanel的相关部分：

private Boolean IsClearingControls { get; set; } = false;
    private EventHandler OnBeforeClearHandler = null;
    private EventHandler OnAfterClearHandler = null;
    ...
    protected override Control.ControlCollection CreateControlsInstance()
    {
        this.OnBeforeClearHandler = (object o, EventArgs e) =>
        {
            this.IsClearingControls = true;
        };

       this.OnAfterClearHandler = (object o, EventArgs e) =>
        {
            this.FlowPositionX = 0;
            this.FlowPositionY = 0;
            this.FlowingHeight = 0;
            this.IsClearingControls = false;
        };

        ExtendedControlCollection ecc = new ExtendedControlCollection(this);
        ecc.OnBeforeClear += this.OnBeforeClearHandler;
        ecc.OnAfterClear += this.OnAfterClearHandler;

        return ecc;
    }
    ....

    protected override void OnControlRemoved(ControlEventArgs e)
    {
        base.OnControlRemoved(e);
        if (!this.IsClearingControls)
        {
            //Recalculate positions for Controls based on removed control
            //else: Do nothing, clearing is handled in OnAfterClear() Listener.
        }
    }
    ...
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (this.OnBeforeClearHandler != null)
            {
                ((ExtendedControlCollection)this.Controls).OnBeforeClear -= this.OnBeforeClearHandler;
                this.OnBeforeClearHandler = null;
            }

            if (this.OnAfterClearHandler != null)
            {
                ((ExtendedControlCollection)this.Controls).OnAfterClear -= this.OnAfterClearHandler;
                this.OnAfterClearHandler = null;
            }
        }

        base.Dispose(disposing);
    }