private void btnMaterial_Click(object sender, EventArgs e) { int nI = 0; foreach (Form form in Application.OpenForms) { if (form.Name == "frmMaterialView") { form.Activate(); form.BringToFront(); nI++; } } if (nI == 0) { frmMaterialView MaterialView = new frmMaterialView(); MaterialView.MdiParent = this; this.splitContainer2.Panel2.Controls.Add(MaterialView); MaterialView.Dock = DockStyle.Fill; MaterialView.Show(); } }