private void studentsPerSubjectToolStripMenuItem_Click(object sender, EventArgs e) { if (StudentsPerSubjectParameters == null) { StudentsPerSubjectParameters = new frmStudentsPerSubjectParameters(); } else { if (StudentsPerSubjectParameters.Created == false) { StudentsPerSubjectParameters = new frmStudentsPerSubjectParameters(); } } StudentsPerSubjectParameters.MdiParent = this; StudentsPerSubjectParameters.Show(); StudentsPerSubjectParameters.Activate(); }