private void ProveedoresToolStripMenuItem_Click(object sender, EventArgs e)
        {
            FormProveedores ventanap = new FormProveedores();

            ventanap.MdiParent = this;
            ventanap.Show();
        }
 private void Form1_Load(object sender, EventArgs e)
 {
     Frm2           = new FormProveedores();
     Frm2.MdiParent = this;
     Frm2.Show();
 }