画一个临时的红圈(在重生时被移除)

using System;
using System.Collections.Generic;
using System.Text;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.Geometry;
using aGi = Autodesk.AutoCAD.GraphicsInterface;
namespace MyTest
{
    public class testing
    {
        private DBObjectCollection m_mrkers = new DBObjectCollection();
        private IntegerCollection intColl = new IntegerCollection();
        [CommandMethod("TempCirc")]
        public void tempcirc()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            doc.CommandWillStart += new CommandEventHandler(doc_CommandWillStart);
            Point3d ctrPt = new Point3d(100,100,0);
            Circle circ = new Circle(ctrPt, Vector3d.ZAxis, 5);
            circ.ColorIndex = 1;
            aGi.TransientManager.CurrentTransientManager.AddTransient(circ, aGi.TransientDrawingMode.DirectTopmost, 128, intColl);
            m_mrkers.Add(circ);
        }
        void doc_CommandWillStart(object sender, CommandEventArgs e)
        {
            if (e.GlobalCommandName.Contains("REGEN"))
            {
                ClearMarkers();
                Document doc = Application.DocumentManager.MdiActiveDocument;
                doc.CommandWillStart -= new CommandEventHandler(doc_CommandWillStart);
            }
        }
        private void ClearMarkers()
        {
                aGi.TransientManager.CurrentTransientManager.EraseTransient(m_mrkers[0], intColl);
                m_mrkers[0].Dispose();
                m_mrkers.Clear();
            }
        }
    }

doc.CommandWillStart += New CommandEventHandler(AddressOf doc_CommandWillStart)

AddHandler doc.CommandWillStart, New CommandEventHandler(AddressOf doc_CommandWillStart)

'doc.CommandWillStart -= New CommandEventHandler(AddressOf doc_CommandWillStart)

RemoveHandler doc.CommandWillStart, AddressOf doc_CommandWillStart

        Private Sub ClearMarkers()
            If (m_mrkers.Count) > 0 Then
                For i As Integer = 0 To m_mrkers.Count - 1
                    aGi.TransientManager.CurrentTransientManager.EraseTransient(m_mrkers(i), intColl)
                    m_mrkers(i).Dispose()
                Next
            End If
        End Sub