问Visio绘图控件:关闭模式对话框后某些事件没有响应

EN

using Visio = Microsoft.Office.Interop.Visio;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Dialog: Form
    {
        public Dialog()
        {
            InitializeComponent();
        }
    }


    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            axDrawingControl1.Src = "";
            axDrawingControl1.Document.Application.MarkerEvent += Application_MarkerEvent;

            Visio.Shape shape = axDrawingControl1.Document.Application.ActivePage.DrawRectangle(0, 0, 1, 1);
            shape.AddSection((short)Visio.VisSectionIndices.visSectionAction);
            shape.AddRow((short)Visio.VisSectionIndices.visSectionAction, 0, (short)Visio.VisRowTags.visTagDefault);
            shape.CellsSRC[(short)Visio.VisSectionIndices.visSectionAction, 0, (short)Visio.VisCellIndices.visActionMenu].FormulaU = "\"Dummy\"";
            shape.CellsSRC[(short)Visio.VisSectionIndices.visSectionAction, 0, (short)Visio.VisCellIndices.visActionAction].FormulaU = $"QUEUEMARKEREVENT(\"abc\")";

            shape = axDrawingControl1.Document.Application.ActivePage.DrawOval(0, 0, 1, 1);
            shape.AddSection((short)Visio.VisSectionIndices.visSectionAction);
            shape.AddRow((short)Visio.VisSectionIndices.visSectionAction, 0, (short)Visio.VisRowTags.visTagDefault);
            shape.CellsSRC[(short)Visio.VisSectionIndices.visSectionAction, 0, (short)Visio.VisCellIndices.visActionMenu].FormulaU = "\"Dummy\"";
            shape.CellsSRC[(short)Visio.VisSectionIndices.visSectionAction, 0, (short)Visio.VisCellIndices.visActionAction].FormulaU = $"QUEUEMARKEREVENT(\"def\")";
        }

        private void Application_MarkerEvent(Visio.Application app, int SequenceNum, string ContextString)
        {
            Dialog dlg = null;
            dlg = new Dialog();
            dlg.ShowDialog();
            //I close form
            dlg.Dispose();
        }
    }
}