private void borçluEkleToolStripMenuItem_Click(object sender, EventArgs e)
 {
     foreach (Form frm in this.MdiChildren)
     {
         frm.Close();
     }
     borcluEkle           = new BorçluEkle();
     borcluEkle.MdiParent = this;
     borcluEkle.Show();
 }