private void btnItemTotal_Click(object sender, EventArgs e) { foreach (Form form in Application.OpenForms) { if (form.Name == "frmSumMaterialListView") { form.Focus(); return; } } frmSumMaterialListView frmSumMaterialListView = new frmSumMaterialListView(); frmSumMaterialListView.MdiParent = this.ParentForm; frmSumMaterialListView.BringToFront(); frmSumMaterialListView.Show(); }