private frmMenu frmMenu = new frmMenu();
        public frmMain()
        {
            InitializeComponent();
        }
        private void frmMain_Load(object sender, EventArgs e)
        {
            frmMenu.P_fm = this;
            frmMenu.Show(this.dockPanelMain);
        }
       
      
        public bool CheckFormIsOpen(string formname)
        {
            bool remark = false;
            for (int a = 0; a < base.MdiChildren.Length; a++)
            {
                if (formname.Equals(base.MdiChildren[a].GetType().Namespace + "." + base.MdiChildren[a].GetType().Name))
                {
                    base.MdiChildren[a].Activate();
                    remark = true;
                }
            }
            return remark;
        }

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using WeifenLuo.WinFormsUI.Docking;

namespace e24tt
{
    public partial class frmMenu : DockContent
    {
     
     
        public frmMenu()
        {
            InitializeComponent();
        }
        //FormSub:
        private frmMain fm;
        public frmMain P_fm
        {
            get { return fm; }
            set { fm = value; }
        }
        private void frmMenu_Load(object sender, EventArgs e)
        {
            trvMenu.ExpandAll();
        }

        private void trvMenu_AfterSelect(object sender, TreeViewEventArgs e)
        {
            try
            {
                //FormSub:
                //在需要对其调用者（父）刷新时
    
               
                if (this.trvMenu.SelectedNode.Text != null)
                {
                    if (this.trvMenu.SelectedNode.Tag != null)
                    {
                        string formname = this.trvMenu.SelectedNode.Tag.ToString();
                        if (!fm.CheckFormIsOpen(formname))
                        {
                            fm.OpenChildForm(formname);
                        }

                    }
                }
                fm.Text = "24TT设置 之 " + this.trvMenu.SelectedNode.Text;
            }
            catch { }
        }
    }
}