private void metroTile4_Click(object sender, EventArgs e)
        {
            frmCourse f = frmCourse.Instacne();

            //f.MdiParent = this;
            f.Show();
            f.Focus();
        }
        private void 课程信息ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmCourse f = frmCourse.Instacne();

            f.MdiParent = this;
            f.Show();
            f.Focus();
        }
 private void toolStripButton_Click(object sender, EventArgs e)
 {
     try
     {
         ChangeEnabledState();
         this.Validate();
         this.courseBindingSource.EndEdit();
         this.tableAdapterManager.UpdateAll(this.student_Manage_DB);
     }
     catch (Exception ex)
     {
         DialogResult result = MessageBox.Show("该课程号已经存在,请重新确认", "操作提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);
         frmCourse    f      = new frmCourse();
         this.Close();
         f = new frmCourse();
         f.Show();
         f.Focus();
         return;
     }
 }