void formImport_FormClosing(object sender, FormClosingEventArgs e) { formImport = null; }
private void btnExport_Click(object sender, EventArgs e) { if (formImport == null) { formImport = new FormImport(); formImport.WindowState = FormWindowState.Maximized; formImport.FormClosing += formImport_FormClosing; formImport.MdiParent = this; } formImport.Show(); formImport.BringToFront(); }