/// <summary>
        /// 禁止子窗體被重複開啟(開啟窗體為預設大小)
        /// </summary>
        /// <param name="formChild">例項子窗體</param>
        public void FrmDisposeNormal(Form formChild)
        {

            bool isOpened = false;                      //定義子窗體開啟標記,預設位false
            foreach (Form form in
 
 this.MdiChildren)     //迴圈MDI中的所有子窗體
            {
                //銷燬其他不是要開啟的視窗例項
                if (formChild.Name != form.Name)
                {
                    form.Dispose();
                }
                if (formChild.Name == form.Name)          //若該窗體已被開啟
                {
                    formChild.Activate();               
 
//啟用該窗體
                    formChild.StartPosition = FormStartPosition.CenterParent;
                    formChild.WindowState = FormWindowState.Normal;
                    isOpened = true;                    //設定子窗體的開啟標記為true
                    formChild.Dispose();                //銷燬formChild例項
                    break
 
;
                }
            }

            if (!isOpened)                              //若該窗體未開啟,則顯示該子窗體
            {
                formChild.MdiParent = this;
                formChild.Show();
            }

        }
        public void FrmDispose(Form formChild)
        {

            bool isOpened = false;                      //定義子窗體開啟標記,預設位false
            foreach (Form form in this.MdiChildren)     //迴圈MDI中的所有子窗體
            {
                //銷燬其他不是要開啟的視窗例項
                if (formChild.Name != form.Name)
                {
                    form.Close();
                }                
            }
            if (!isOpened)                              //若該窗體未開啟,則顯示該子窗體
            {                
                formChild.Show();
            }

        }
        /// <summary>
        /// 禁止子窗體被重複開啟(開啟窗體為最大化)
        /// </summary>
        /// <param name="formChild">例項子窗體</param>
        public void FrmDisposeMax(Form formChild)
        {

            bool isOpened = false;                      //定義子窗體開啟標記,預設位false
            foreach (Form form in this.MdiChildren)     //迴圈MDI中的所有子窗體
            {
                //銷燬其他不是要開啟的視窗例項
                if (formChild.Name != form.Name)
                {
                    // form.Dispose();
                    form.Close();
                }
                if (formChild.Name == form.Name)          //若該窗體已被開啟
                {
                    formChild.Activate();               //啟用該窗體
                    formChild.StartPosition = FormStartPosition.CenterParent;
                    formChild.WindowState = FormWindowState.Maximized;
                    isOpened = true;                    //設定子窗體的開啟標記為true
                    formChild.Close();                //銷燬formChild例項
                    break;
                }
            }

            if (!isOpened)                              //若該窗體未開啟,則顯示該子窗體
            {
                formChild.MdiParent = this;
                formChild.WindowState = FormWindowState.Maximized;
                formChild.Show();
            }
        }